Help! 89 Won't Idle!

[CulverC4]

Hey Guys,
I just got my baby back after 2 months at Coast Corvette in Anaheim getting some body and paint work done. Well, I got her back home to the Culver City area, about 30-45 minute drive on the highway, and the ride was great. But a couple of days later, when I went in to a local shop to get my balljoints replaced the car began the stutter, RPM's fell to about 400 and she then stalled out. The mechanic was at the helm, road test, and he restarted and revved the engine which seemed to "reset" the problem. We finished the road test and I drove home with no further incident. He mentioned that it might be the idle air control valve, which is what I was thinking.
Anyways, I got home and still drove her the following 2 days with no incident. Well, yesterday (Sunday) I took her for a nice long cruise through PCH and up the Malibu Canyons, drove home and parked her (No incident), but when I came out a couple of hours later and started her she began to act up again. I revved her up like the mechanic did, but as soon as I let off the gas (about 1-2 seconds later) the car dropped to 400 rpms and soon stalled out again. I tried this about 4 times, all with the same result. I ordered a new IAC valve from MidAmerica as well as a new EGR valve that I needed to replace anyways. Is there anything else I should check out? Oh, I also heard the relay located on the driver's side wheel well clicking like crazy the day at the shop, but not now. Any connection between the two possible?

Thanks in advance,
Jose

 

[CulverC4]

Status update

I just disconnected the IAC, started the engine, got the same stutter but revved her up to 2400 to keep her going. After I let off the gas though she kept revving at 1000 rpm steadily. I shut her off and did it again, but this time she went back down to about 400 rpm and stuttered, but did not stall! On the verge though. I would stab the gas and the rpm's went up smoothly enough, but would come back down to the 400 rpm range and putter as if she was about to die but staying alive. Does this confirm that the IAC valve needs replacement? Should I also replace the TPS while I'm at it?
Thanks,
Jose

 

[CulverC4]

Idle Repaired

So I had the IAC valve replaced and voila! She idles again, but I'm still a little concerned as I find that she drops down to a steady 500 rpm or so at times when in drive and fully stopped. If I throw the A/c on the revs steady out at 700 rpm or so which provides a smoother idle. I'm replacing the egr valve next so I'm hoping it's a simple vacuum issue.

 

[So Bay Vetter]

I know this may be a stupidly simple suggestion and you may have solved the problem by now but, did you clean the air filter after the body shop was done? Sanding dust, particularly if it was hosed down under the hood can get real sticky in the filter and suffocate the engine.

 

[sstearns2]

I had an 89 and had problems at idle. It would stumble and want to die every couple times I drove it. It turned out to be the two relays that are behind the battery on the firewall. One is the MAF burnoff relay and I can remember what the other is. They're cheap. My mechanic insisted that it couldn't be the problem and it didn't really make sense to me either, but it never happened again after I changed the relays.

If you haven't already it's a good idea to pull the throttle body off and clean it out or at least open the throttle plates and wipe out the bores if you don't want to pull it off the engine. A lot of gunk builds up in there.

Scott