High Idle again! help please

[vallentinerocks]

OK, so i had a high idle issue a few weeks back and had posted on another person's thread with a similar idle problem. there were some suggestions about maybe EGR(vanbidder) and perhaps check gaskets, but i dont know if they were intended for me or the other guy.

1994 with 3.4 and 5 speed. no mods.

Anyways, my problem was idle jumped up to about 1500rpms. Disconnecting battery and resetting computer was temporarily bringing the idle RPM's back to around 900 but only on a temporary basis. day by day, i would start motor, and rpms would be back up again.
I ended up putting a new IAC in a short while back, and it seemed to have cured the high idle issue. didnt have any problems for over a week, until last night. Idle is high again, around 1600, and this time resetting the computer attempts did not bring idle back down to normal idle like before, and also my SES came on and stayed on this time. I am tempted to exchange the IAC i just got from Kragen for another one, because the new IAC took care of the problem for over a week without any issues. what are the chances the new IAC is faulty? plus, an exchange wont cost me anything.
If it doesnt fix the idle, i guess i will need to get a diagnostics performed. that is the proper step before replacing things like EGR or other higher priced items, right?
Just want to have a better idea of what i may be looking towards if the high idle issue is NOT due to the IAC. Vacumm leaks, what do i spray to detect? besides EGR, IAT and computer, what else could cause high idle like i have been having? could there be any defect in the fuel pump itself to cause high idle? car just had tune up, and passed smog less than a month ago, and runs great for the most part.no starting problems, doesnt stall or run rough or anything. just been dealing with the high idle issue. thats the only thing. let me know guys! thanks for help in the past.

[ March 16, 2006, 08:46 AM: Message edited by: vallentinerocks ]

[BobbyZ72]

Go for it, change that iac again. Check your mass air flow senser, it could have dirt build up on it. I doubt its your fuel pump. What about your tps, could it be seeing your throttle as slighty open?

[CDNFB]

Check for vacuum leaks. You will get excessive idle RPM if the leak is large enough to overwhelm the control range of the IAC.

And don't just look at gaskets as the primary cause. You can get leaks from diaphrams and solenoids as well.

DZ

[vallentinerocks]

Thanks BobbyZ72 and CDNFB for responding. with daylight now to actually see, and after calling my ex-roomate who owns a smog shop, he told me it sounds like a vacuum leak. Well, he and CDNFB were right on! i dont know the actual name, but the vacumm hose right on top of the center of motor that runs into a T-SPLIT (The one on the passenger side of the T)had come completely dislodged from the grommet connector. i think it is the opposite side of the vacuum brake boost hose that says Accessory in the Chilton manual, but not quite sure. diagram wasnt all that great. but that was the problem to my high idle issue. it wiggled its way out of its grommet the last time i drove the car a few days ago obviously. it is now secure and wont come off again. What a relief that was! i did however swap out the new IAC for a newer IAC anyway before noticing the vacumm line off.
anyways, everythings great again. thanks for the replies.