I have a Pontiac firebird 1976 with 455 engine and auto transmission. My city where I live, the weather temperature is 120 F so my engine coolant temperature reaches to 220 F during driving. When my e

Have you gone through your entire cooling system like a coolant flush cleaning out all the gunk in your engine as far as any rust that could be in there when you flush it and then put brand new Coolant in and change your thermostat too just do the maintenance of your cooling system and see what happens I don't know if you've done that yet but try that.

Additionally I don't know with the age of that vehicle a 1976 but it might have some kind of temp sensor set up that when it reads it's too hot will try to shut the car down I'm not quite sure but if you do a proper coolant maintenance cooling repair a flush etc. it might tell you a lot I would try that first.

Kindly note that my radiator is new and my coolant is clean and there is no rust or gunk. I remove my thermostat because my city weather is very hot and when i start the engine after 3 minutes the coolant temperature reach to 185 F. I overhauled my water pump as well. really my engine temperature is very high and i installed an extra electrical fan which turn on manually. I don't know why my engine temperature going high when i push acceleration pedal fully, the engine is going to die yesterday again i checked my fuel filter and spark plug every thing was OK

Yeah the way I understand cooling systems is regardless of your temperature outside you're supposed to have a thermostat to regulate when the coolant is moved around in your engine. I think you might have a carburetor issue cuz if you're letting off the pedal after really pushing the pedal hard and it's not idling and it wants to die before it goes into second gear I would think it could be a carburetor issue have you looked at your carburetor?

Yeah. Myself also suspect to my carburetor. I check my carburetor fuel filter and it was clean. when my engine is cool every thing is OK and when it becomes hot i face the problem. something is related to temperature. when engine temperature going up and i push the pedal hard during shifting gear from one to two while the engine RPM going to change; the engine face with lack of fuel or ignition or something else then engine going to die. Many thanks for your advise my friend, i hope so to find the problem when i find it i will share it here for reference