Hi i have a 1986 IROC with a 305 TPI motor. The problem I am having is when the car sits for 4 to 5 hours and I try to start it it wont idle and runs very rough and stalls. I continue to run car untill it gets to operating temperature then car runs great and idles great. I am not that familiar with these cars and was wondering if anyone had any experience with a problem like this or at least where I should start. Thanks :hail:

 

Rough running in open loop mode? There may be a mixture problem that is corrected by the oxygen sensor becoming active and the ECM adjusting mixture accordingly. There may be a low fuel pressure situation, vacuum leak, injector leakage, fuel pressure regulator leakage, PCV valve problem, EGR valve problem, and probably others I am overlooking.