Idle problem

[Steves LX]

So about a week ago after I had been driving for about 35 minutes I went to stop for a traffic light and my idle wouldn't drop below 1500. So I pulled over shut the car off, looked under the hood, and checked all my sensor connections and everything was fine. So I started the car back up and my idle was back to normal. The car never did it again until this past Friday. Same deal I had been driving for about 35 minutes or so and sure enough it started acting up again. So when I got home I kept it running and pulled my harness plug off my IAC and the car died. So I plugged it back in and started the car and it went back up to 1500RPM's and I spray all my vacum lines and around by intake and my idle didn't change one bit. So I left the car sit for a few hrs and started it back up and the idle was fine. I need some help here. Any idea's

[facemelter71]

Replace the IAC valve.Its cheap enough to warrent getting and if you personally have never replaced your's,its probly caked with soot and carbon and all kinda of nasty crap.

[Steves LX]

I just replaced this thing back in the summer. Not to say its bad but if the car was running and I unplugged it and the the car died, wouldn't that mean that its working properly.

[Timido]

If it was anouther vaccum leak the car would still run with the Iac unplugged. It does sound like a bad Iac to me. Try giving it a light smack with a hammer or screw driver or try removing it and cleaning out all the carbon in it.

[Steves LX]

O.K. I will try that. Out of curiosity will that also perhaps be the cause of my surging idle and even stalling out from time to time or is that gonna be another problem.

[Timido]

Could be. I would try that first. Anouther thing to do is hold the throttle body open and spray throttle body cleaner up in the throttle body and take an old tooth brush and clean as far up in the throttle body and throttle plate as you can.

[facemelter71]

Also remember that some of your vacuum tubing runs inside to run the climate knob to switch it from the floor-defrost-vent(etc).Listen for leak their also.And sometimes the pcv valve will become loose and the rubber it goes into gets a little nasty and doesnt like to seal all that well.

[Steves LX]

So I pulled my idle air control off and it is clean. I sprayed it with some TB cleaner anyways and I checked my TB and it was clean also but I sprayed it down too. But low and behold my surging idle is still there. I drove the car to work today and evertime I go to stop my RPM's drop down to 100 and then go back up to 700-800 and then back down to around 200 and then back up. Its back and forth back and forth. I noticed that if I am approaching a point on the road where I have to stop and if I just take it out of gear instead of downshifting, the idle for the most part will stay between 700-800 right where I want it but if I downshift it either stalls once I stop or it surging all over the place.