Car Won't Idle Down

Asked on December 24, 2011
1991 Chevrolet Lumina Engine Problem with 280000 miles
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Car Won't Idle Down
I have a 1991 Chevrolet Lumina (Car) 3.1L V6 that won't idle down. When you start the car, it goes into fast idle and will not idle down (even when warm) until you put it in gear, but then when you push in on the gas the car engine lugs down and most of the time stalls. If the car doesn't stall, when you get out on the road and get going, the engine will surge up and down like it not getting gas or something. It has finally gotten so bad I have parked the car until I hear from you all. When the car is just sitting in the driveway the engine runs good and smooth, except for being in fast idle.
Asked by Pilotbill

Replied on December 24, 2011
How fast of a idle?Have you checked the coolant temp sensor yet?Any codes in the computer?
Answered by saturntech9 (expert)
6,878 answers provided

Replied on December 24, 2011
You may have a bad IAC ( idle air control) but try eliminating any vacuum leaks and cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.
Answered by Wrenchtech (expert)
7,959 answers provided
Replied on December 24, 2011
The idles symptoms maybe but the surging while driving etc does fit for a iac issue.
Answered by saturntech9 (expert)
6,878 answers provided
Replied on December 24, 2011
i would look for a vacuum leak. If all hoses are ok, look at the idle speed control motor failing. Carbon build up in the throttle body is common with your mileage.

Roy
Answered by ASEMaster6371 (expert)
1,642 answers provided

Replied on December 24, 2011
Your welcome but what the other moderators have missed was you said the car surges while going down the road thats not going to be a iac and I would say a vacuum leak wouldnt do that ethier. There only thinking that its surging at idle and has a high idle. Lets stick to this question please post all your responses to this question. If you start a new question to post a reply to this one I wont get a email saying you posted a reply to the question.I would check for codes first do you know how to do that on this car?
Answered by saturntech9 (expert)
6,881 answers provided

Reply to Mr SATURNTECH, Could you tell me how to check for codes? Thank You Very Much.