OOOkkk well heres the story, got my daily driver 84 Se with stock Duke just rebuilt due to bad piston, was bored, ringed, new pistons, bearings and oil pump, water pump, radiator fan and radiator also new and all lines flushed also have tried two different distributors with same issues. The PROBLEM, going to work in the mornings temp will stay around 180-190, coming home thought will go above 210 to 220 and the engine will like to die at stop lights and even while at cruising speeds but will start right back up instantly with key off and back on but will NOT do this in the morning going to work and my commute is about 30 miles one way and the car sits about 9 hrs untill i go home. the car acts the same with or with out a thermostat. question is what could i be doing wrong here, i would like to stay around 190 on the temp.

What kind of temperature difference (atmosphere, not engine temp) is there between mornings and evenings there?

I would say somethign is getting hot in the afternoon, like the coil or ignition module or whatever it has. Hard to tell if it is electric or fuel, but electric usually just dies and fuel sort to tapers off. I am thinking somethign hot in the electric end of things. Larry

Its about 75 in the morning and evenings its around 100, ive had three different coils,distributors and injectors.

do you have AC on the car if you do then your cooling fan should cut on when you cut the AC on.So you can forget that as a problem for the overheating but if you dont have AC the original fan switch on the motor is set at 210 before it cuts the fan on.Iwas having the same problem so i changed the thermostat to a 180 from the 195 and i put in a new fan switch to a 190.had to modify the relay for the fan to a later model GM with the same fan setup.but it took care of my overheating problem.As for the cutting off problem there are a lot of variables it sounds like you have tried all the things on the motor itself.So if i were to guess and thats all I'm actually doing i would look into the fuel pump and relay.

a/c is INOP but with a/c switch on the fan comes on and i turn it on when it gets around 190

1. 210-220 is Normal for Fiero and Many others.

2. Your problem has nothing to do w/ coolant temp.

Try take off console so ECM get allot of air to cool. If that helps then get another ECM.
See my Cave, ECM Heat

Check volts to fuel pump. ALDL pin G and ground. Should be close to battery/alt volts.
See my Cave, Electric Motors

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The ecm has been behind the drivers seat for a while now because i was thinking of that too but will try another ecm