But if the car starts fine in the morning, then the fuel has not evaporated or boiled off since you parked it last night.
as for the thermostat; it sets the MINIMUM cooling system temp and has nothing to do with the maximum. I get where your thinking is going, but I would try very hard to run the engine closer to 195 than to 160; on the minimum.
if your car is a mechanical lifter slanty, the first thing I would do is lash the valves.
If it's a 318, I would pop the hood when you shut it off and remove the air cleaner lid. Then I would sit there and watch and listen, for at least 10 minutes. If you hear the gas percolating in the bowl, and see the smoke coming up out of the carb, both together; there is your problem. That ain't supposed to happen.