If a 180 degree thermostat causes fuel to “collect” in the manifold (here is a tuning tip…fuel is ALWAYS puddled in the bottom of the manifold as that is what the engine runs off of, the puddle so you need to rethink that) and that collection of fuel is too much you need to fix the tune up.
These engines run off the puddle. Take away the puddle and they don’t run. Driving with an O2 sensor would allow you to see this.
If the engine runs rich after lowering the coolant temperature then fix the rich condition. Don’t use excess engine heat to fix the tune up.