I would also add drilling a 1/8 hole on two opposite side of the thermostat to allow any trapped air to escape.
I've done that on every thermostat I've installed in Las Vegas. If you drive a ford or chevy you can get the thermostat with the holes already drilled.
I cleaned the throttle body and replaced the intake hose from the TBI to the air cleaner . I think it was the TBI cleaning that did the trick. There was enough caked on mess that I'm sure it was keeping the throttle valve partially open.
The vechicle is running rich all the time. I'm cleaning the throttle body and replacing a cracked air intake hose.
I've got no check engine light. What would cause it to run rough but not cause a check engine light?
I've got one coming.
Go to the exhaust, with the engine running you should be able to feel the "pulse" of each cylinder firing. If its a solid flow of exhaust gases then Id think it's a clogged Catalytic converter
I did. Checked all the hoses where tight and not cracked. Sprayed carb cleaner all around the engine in hopes of finding a leak, no change in RPM. Changed cap and rotor, has new plugs. Runs much better when warmed up for 10 minutes.