I finally bought the z28 Ive been looking for. I picked up a nice 94 z28 with an auto trans. After sitting for a while it take an extremely long time to start, about 7 to 10 seconds of cranking, then after its warmed up and Im in traffic at a stop the idle will intermittently spike up a little above 1k rpm. When I have it in park it will jump way higher than that. I have no idea where to start with this, if anyone knows what it could be please let me know, Thanks

 

Start out by checking the fuel pressure. Hard start after sitting for a while could be caused by a weak fuel pump.

 

really, I did notice that the pump seemed loud. But I though that was normal on all GM's

 

Probably wouldnt hurt to change the fuel filter too.

 

I just posted this on another guy's question and it might help you too. Check all of the vacuum hoses. I had a wierd idling for a while and just found out that I had a broken vacuum hose coming out the passenger side of my throttle body. Put a new one in for $1.05 and it runs great. Might not be what is wrong with yours but for $1.05 I would make sure to check it out. Good luck.

 

I remember that hose from another, This one is ok, I just cleaned out the completed throttle body assembly and IAC valve, and re-gasketed the whole thing, just a few minutes ago I heard it reving again. I checked fuel pressure this morning, everything checks out. My next plan is to use the OTC.