diff --git a/src/smt/smt_context.cpp b/src/smt/smt_context.cpp
index 87878ab6e..e8f82b44e 100644
--- a/src/smt/smt_context.cpp
+++ b/src/smt/smt_context.cpp
@@ -3617,7 +3617,7 @@ namespace smt {
        \remark A logical context can only be configured at scope level 0,
        and before internalizing any formulas.
     */
-    lbool context::setup_and_check(bool reset_cancel, bool enable_parallel_param_tuning) {
+    lbool context::setup_and_check(bool reset_cancel) {
         if (!check_preamble(reset_cancel)) return l_undef;
         SASSERT(m_scope_lvl == 0);
         SASSERT(!m_setup.already_configured());
@@ -3625,7 +3625,7 @@ namespace smt {
 
         if (m_fparams.m_threads > 1 && !m.has_trace_stream()) {
             expr_ref_vector asms(m);
-            parallel p(*this, enable_parallel_param_tuning);
+            parallel p(*this);
             return p(asms);
         }
 
@@ -3685,15 +3685,15 @@ namespace smt {
         }
     }
 
-    lbool context::check(unsigned num_assumptions, expr * const * assumptions, bool reset_cancel, bool enable_parallel_param_tuning) {
+    lbool context::check(unsigned num_assumptions, expr * const * assumptions, bool reset_cancel) {
         if (!check_preamble(reset_cancel)) return l_undef;
         SASSERT(at_base_level());
         setup_context(false);
         search_completion sc(*this);
         if (m_fparams.m_threads > 1 && !m.has_trace_stream()) {            
             expr_ref_vector asms(m, num_assumptions, assumptions);
-            IF_VERBOSE(1, verbose_stream() << "Starting parallel check with " << asms.size() << " assumptions and param tuning enabled: " << enable_parallel_param_tuning << "\n");
-            parallel p(*this, enable_parallel_param_tuning);
+            IF_VERBOSE(1, verbose_stream() << "Starting parallel check with " << asms.size() << " assumptions\n");
+            parallel p(*this);
             return p(asms);
         }
         lbool r = l_undef;
diff --git a/src/smt/smt_context.h b/src/smt/smt_context.h
index a363548e4..ce6b0df65 100644
--- a/src/smt/smt_context.h
+++ b/src/smt/smt_context.h
@@ -1690,7 +1690,7 @@ namespace smt {
 
         void pop(unsigned num_scopes);
 
-        lbool check(unsigned num_assumptions = 0, expr * const * assumptions = nullptr, bool reset_cancel = true, bool enable_parallel_param_tuning = true);
+        lbool check(unsigned num_assumptions = 0, expr * const * assumptions = nullptr, bool reset_cancel = true);
 
         lbool check(expr_ref_vector const& cube, vector<expr_ref_vector> const& clauses);
 
@@ -1700,7 +1700,7 @@ namespace smt {
 
         lbool preferred_sat(expr_ref_vector const& asms, vector<expr_ref_vector>& cores);
 
-        lbool setup_and_check(bool reset_cancel = true, bool enable_parallel_param_tuning = true);
+        lbool setup_and_check(bool reset_cancel = true);
 
         void reduce_assertions();
 
diff --git a/src/smt/smt_internalizer.cpp b/src/smt/smt_internalizer.cpp
index b86af05ac..e1eda24f9 100644
--- a/src/smt/smt_internalizer.cpp
+++ b/src/smt/smt_internalizer.cpp
@@ -990,8 +990,7 @@ namespace smt {
 
     
     void context::undo_mk_bool_var() {
-        SASSERT(!m_b_internalized_stack.empty(ue key per literal
-            m_lit_scores[lit.sign()][v] += 1.));
+        SASSERT(!m_b_internalized_stack.empty());
         m_stats.m_num_del_bool_var++;
         expr * n              = m_b_internalized_stack.back();
         unsigned n_id         = n->get_id();
diff --git a/src/smt/smt_parallel.cpp b/src/smt/smt_parallel.cpp
index 5de53176e..ee2d06cdb 100644
--- a/src/smt/smt_parallel.cpp
+++ b/src/smt/smt_parallel.cpp
@@ -68,7 +68,7 @@ namespace smt {
     lbool parallel::param_generator::run_prefix_step() {
         if (m.limit().is_canceled())
             return l_undef;
-        IF_VERBOSE(1, verbose_stream() << " PARAM TUNER running prefix step\n");
+        IF_VERBOSE(1, verbose_stream() << " PARAM TUNER running prefix step with conflicts " << m_max_prefix_conflicts <<"\n");
         ctx->get_fparams().m_max_conflicts = m_max_prefix_conflicts;
         ctx->get_fparams().m_threads = 1;
 
@@ -76,7 +76,7 @@ namespace smt {
         ctx->m_recorded_cubes = &m_recorded_cubes;
         lbool r = l_undef;
         try {
-            r = ctx->check(0, nullptr, true, false);
+            r = ctx->check(0, nullptr, true);
             IF_VERBOSE(1, verbose_stream() << " PARAM TUNER: prefix step result " << r << "\n");
         } 
         catch (z3_error &err) {
@@ -126,7 +126,7 @@ namespace smt {
                 if (m.limit().is_canceled())
                   return;
                 // the conflicts and decisions are cumulative over all cube replays inside the probe_ctx
-                lbool r = probe_ctx->check(cube.size(), cube.data(), true, false);               
+                lbool r = probe_ctx->check(cube.size(), cube.data(), true);               
                 IF_VERBOSE(2, verbose_stream() << " PARAM TUNER " << i << ": cube replay result " << r << "\n");                
             }
             unsigned conflicts = probe_ctx->m_stats.m_num_conflicts;
@@ -340,10 +340,9 @@ namespace smt {
 
     parallel::param_generator::param_generator(parallel& p)
         : b(p.m_batch_manager), m_p(p.ctx.get_params()), m_l2g(m, p.ctx.m) {
-        // patch fix so that ctx = alloc(context, m, p.ctx.get_fparams(), m_p); doesn't crash due to some issue with default construction of m
-        ast_translation m_g2l(p.ctx.m, m);
-        m_g2l(p.ctx.m.mk_true());
 
+        m.copy_families_plugins(p.ctx.m);
+        SASSERT(p.ctx.get_fparams().m_threads == 1);
         ctx = alloc(context, m, p.ctx.get_fparams(), m_p);
         context::copy(p.ctx, *ctx, true);
         // don't share initial units
@@ -539,7 +538,7 @@ namespace smt {
                                        << bounded_pp_exprs(cube)
                                        << "with max_conflicts: " << ctx->get_fparams().m_max_conflicts << "\n";);
         try {
-            r = ctx->check(asms.size(), asms.data(), true, false);
+            r = ctx->check(asms.size(), asms.data(), true);
         } catch (z3_error &err) {
             b.set_exception(err.error_code());
         } catch (z3_exception &ex) {
@@ -692,6 +691,7 @@ namespace smt {
             scoped_clear(parallel &p) : p(p) {}
             ~scoped_clear() {
                 p.m_workers.reset();
+                p.m_param_generator = nullptr;
             }
         };
         scoped_clear clear(*this);
@@ -701,6 +701,8 @@ namespace smt {
         
         scoped_limits sl(m.limit());
         flet<unsigned> _nt(ctx.m_fparams.m_threads, 1);
+
+        m_param_generator = alloc(param_generator, *this);
         SASSERT(num_threads > 1);
         for (unsigned i = 0; i < num_threads; ++i)
             m_workers.push_back(alloc(worker, i, *this, asms));
@@ -711,13 +713,12 @@ namespace smt {
         sl.push_child(&(m_param_generator->limit()));
 
         // Launch threads
-        vector<std::thread> threads(m_enable_param_tuner ? num_threads + 1 : num_threads); // +1 for param generator
+        vector<std::thread> threads(num_threads + 1); // +1 for param generator
         for (unsigned i = 0; i < num_threads; ++i) {
             threads[i] = std::thread([&, i]() { m_workers[i]->run(); });
         }
         // the final thread runs the parameter generator
-        if (m_enable_param_tuner)
-            threads[num_threads] = std::thread([&]() { m_param_generator->protocol_iteration(); });
+        threads[num_threads] = std::thread([&]() { m_param_generator->protocol_iteration(); });
 
         // Wait for all threads to finish
         for (auto &th : threads)
diff --git a/src/smt/smt_parallel.h b/src/smt/smt_parallel.h
index ea75fc498..9d7834a25 100644
--- a/src/smt/smt_parallel.h
+++ b/src/smt/smt_parallel.h
@@ -36,7 +36,6 @@ namespace smt {
     class parallel {
         context& ctx;
         unsigned num_threads;
-        bool m_enable_param_tuner;
 
         struct shared_clause {
             unsigned source_worker_id;
@@ -136,7 +135,7 @@ namespace smt {
             scoped_ptr<context> ctx;
 
             unsigned N = 4;  // number of prefix permutations to test (including current)
-            unsigned m_max_prefix_conflicts = 1000;
+            unsigned m_max_prefix_conflicts = 1000; // todo- maybe make this adaptive to grow up to 1000 but start with a smaller base
 
             scoped_ptr<context> m_prefix_solver;
             vector<expr_ref_vector> m_recorded_cubes;
@@ -222,14 +221,12 @@ namespace smt {
         scoped_ptr<param_generator> m_param_generator;
 
     public:
-        parallel(context& ctx, bool enable_param_tuner = true) : 
+        parallel(context& ctx) : 
             ctx(ctx),
             num_threads(std::min(
                 (unsigned)std::thread::hardware_concurrency(),
                 ctx.get_fparams().m_threads)),
-            m_enable_param_tuner(enable_param_tuner),
-            m_batch_manager(ctx.m, *this),
-            m_param_generator(enable_param_tuner ? alloc(param_generator, *this) : nullptr) {}
+            m_batch_manager(ctx.m, *this) {}
 
         lbool operator()(expr_ref_vector const& asms);
     };