i just recently bought a 1990 iroc z 5.7L it has a rough idle and feels close to stalling, and when i accelerate it is sluggish and jumpy. want to know how to diagnose this issue to fix it. car also is heating up, figure it could be an issue with the radiator fans, would be nice if that could be explained as well, sorry if this post is in the wrong area. kinda new to cars, just want to know how to fix mine, all help is much appreciated. thank you ahead of time

 

Welcome aboard thirdgen.org.

I moved this to the TPI forum. You're more likely to get help here than in the Engine Swap forum.

 

I'm actually having this same exact problem with my 91 L98. I'm almost positive its a tps issue. I switched out mine with another one I had and I'm still having a problem. I checked the voltage and its at a perfect .54 closed and 4.25 at WOT. Check your tps.

 

Is the SES light on? Codes? What does 'heating up' mean? Is the needle getting into the red? Or just sitting around the 220 mark or a little above?

 

Do you have a fuel pressure gauge? I have the Acton one. As im having the same issue I checked my fuel pressure today and its badly low. At idle im only getting about 30-35 psi. If I rev it the fuel pressure actually DROPS to about 25 psi. I checked my regulator and its good. Im going to check my fuel filter tomorrow. What would cause the fuel pressure to drop?

 

Have you cleaned the IAC pintle and passage, carbon tends to build up effecting idle quality. Have you replaced the plugs, wires, etc., worn out plugs will cause hesitation under load/acceleration.

 

Well I figured out what my problem was maybe this can help you. My fuel pump was on its way out. Luckily it didn't leave me stranded on the side of the road. I replaced it with an extra ACDelco EP241 pump I had laying around. Runs like a champ once again.