I have a 1988 Iroc Z TPI with a 305 and a 5 speed. I'm trying to figure out what the car should be idling at. I have cleaned the throttle body and replaced the TPS and IAC sensors. It is idling around 750 RPM but seems to be running really rich. I'm all out of ideas and in desperate need for some help.

 

I'm running a 89 tune in my 86 to delete the 9th injector, still smells rich on a cold start until it gets up to opetrating temp.. check your voltage at the tps and reset the iac maybe?

 

The voltage is sitting right at .54 on the TPS and I also have reset the IAC. It seems like it like to idle around 850 RPM without smelling unburned fuel but then again the tach may not be accurate. I'm just running out of ideas

 

You might want to get a fuel pressure tester. Watch after prime is the pressure drops. If it drops fast you have leaking injectors or a rip in the fpr diaphragm. To check the diaphragm pull the vacuum hose going to it and look for raw fuel.

 

I noticed today that if I put a paper clip in the A and B port on the ALDL and unplug the IAC harness that the car idles perfect. I'm starting to wonder if the new IAC valve I put in is defective. I have verified that I don't have any vacuum leaks. I'm trying to get my hands on a fuel pressure tester

 

A cheapo bluethooth aldl 'scanner' from ebay will tell you loads of stuff you need to know.
Also maybe you didnt reset the IAC correctly.