I took the 89 RS back because of title problems and bought a 91 z28 5.7. I drove the car all evening off and on for a few hours then got home and offered to take the wife for a ride. As soon as i started it up i got an ses light and tried to drive away. It was stumbling really bad under light acceleration up until about 2000rpm or so (tach is way off) If i floor the car it runs fine but with light acceleration (normal driving) it runs like crap. Got back home checked codes, got nothing. I noticed before that there are two hard vacuum lines under the intake on the pass side that are disconnected but, i bought it like that and it was running fine. If i leave it alone for a while and get back in for a drive its fine for a a minute or soon then i get the light and it starts to run like crap. I'm plagued with these little BS problems. Someone please help.

 

the stumbleing sounds like. ur maf i had that problem once in a while and it was my connection on the maf that the harness goes in to had some debri in it. sometimes it would act fine sometimes it woulndt. the 2 hard vac lines are prolly for egr when the car is cold u wouldnt notice it that much, but when it warms up it would run like **** without them lines connected.

 

Actually, its a speed density car. The vacuum line under the map came disconnected. The car does run like crap when it warms up. Where do those lines go? I bought a haynes shop manual and its not worth $2.