2002 Envoy problems with stalling and high idle

[MissP1971]

I have a 2002 4WD GMC Envoy SLE that has had several problems in the past three months. I’ll be at a stop light and the RPM jumps up to 1200 then down to 400 then up to 1000 then down to 200 and then it finally stalls. I can be at a stop light and the car will jerk forward which causes me to apply more pressure on the brake. Then I notice the RPM jumps up to 900 – 1200 as if the gas pedal is being pushed on. It continues to do this until I turn the ignition off. Sometimes when I coast in traffic and then press on the gas, the car hesitates for a second and sort of jerks forward.

It's been hard for my mechanic to diagnose the problem as the service engine light doesn't always come on. When it does, I take it to the shop and the mechanics fix the problems associated with the errors. I've had the throttle body cleaned, new air filter, new fuel filter along with a flush of the fuel lines, new spark plugs, as well as a tune-up.

After all this work, the car ran fine for a few days then all of a sudden the same problems have crept up again. The service engine light came on after the car was restarted due to a stall but then went out by the next morning. I'm tired of taking my car to the shop every week. What can be causing these problems?

Thanks for any help</SPAN>

[rtobrian]

Check all the vacuum lines for leaks. I'm no mechanic but that's the first thing i'd do.

[accutechautomotive]

check for codes if engine light is on possb cause is idle control motor called an iac

[dougieb513]

I have the same problem in my 2003 GMC Envoy XL SLE. I just noticed the problem about a week ago and as of now the problem is intermittent. Usually after stopping the car and shutting down the engine the problem will go away. Sometimes it stops for a few minutes, other times it stops for a few days. I am completely clueless as to the cause. Any help would be appreciated.

Thanks

[maxwedge]

There are many software updates for similar idle speed/control issues. I would suggest to both of you let a dealer look at these issues.

[Schrade]

Vacuum leak (unless a TSB exists)

Loping idle is vacuum leak. 30 year old lawnmower, or a new car on the lot. If it sucks air where it ain't supposed to, it lopes.

Brick on pedal, block TB arm, anything to get a STEADY idle. 1200rpms or so... Feed starting fluid spray, A LITTLE AT A TIME, EVERYWHERE. Rev increase is the leak.

In a tough spot to pinpoint? Light a book of matches, blow it out while the heads are burnin', and feed the smoke to the leak.

[amageed]

my 2003 Envoy is doing the exact same thing...wants to jump forward when sitting at traffic light and idling is irregular. No ideas???

[accutechautomotive]

Change the idle air cont and your probl will be fixed

[Botamer]

Had the same problem with my 04 Envoy. I cleaned the throttle body and cured all ills.