06 Cobalt Rough Idle/Stall when stopping or quick deceleration

Hello All,

Here is the problem I have.

06 Cobalt LT 2.2l 103065 Miles

When decelerating on the freeway to come to a virtual stop for traffic, when stopping at a stop light, when pulling out of the driveway, or at any point when the RPM's fall quickly to idle speed I have an irratic idle.

Idle will fluctuate between 300-750 rpms

Normal idle is around 750 rpms

This morning it actually stalled when I was pulling up to a stop sign to pull out of my subdivision. It did restart right away.

When the Idle is rought the lights dim on the car, power steering becomes weak, and other problems you would expect when your idle drops and your car is about to stall.

No check engine lights come on at all (I wish they did, I have a nice scantool).

If I decelerate slowly, or have been driving at even driving conditions (not alot of accelerating then decelerating) this doesn't really happen.

Any ideas? Has anyone had this happen?

I just bought this car alittle over a month ago and rely on it so I need to figure this out and get it fixed.

Sounds like either air or fuel is having issues getting to the motor, when did you last clean/change your airfilter? Did you change your fuel filter at any point in time? Thats just where I'd start.

Small chance this is an oil issue as well, last oil change? Use the correct viscosity? Whats the weather like there?

mine did this i change all the filters stopped since then

Also, welcome to the forum.

I have an 06 as well and I changed plugs and changed filters like they stated and I've been ok since....

Yeah I'd say either air filter, fuel filter, or Idle Air Control valve (IAC). Either way I'd dump a can of seafoam into the fuel tank to see if it improves at all.

try cleaning your maf sensor and throttle body. check your air filter. after that, change your plugs. after that, start testing fuel pressure for a bad fuel filter. what's with this seafoam stuff? guys cut that shit out it's no good.

Clean your throttle body

This may be a dumb question but I desperately need help. I am having trouble as mentioned by the priginal poster. The first thing I did was hook it to my actron obd 2 scanner however no codes are coming back which wasn't much of a surprise because i have yet to get any warning or check engine lights. However my problem seems to be a bit more severe. it started about a week ago when I would go to slow down or stop at a stop sign or red light the engine would bog and stutter enough to shake the whole car and make the rpm needle jump around. At first thats all it would do and after a scond of being stopped it would correct itself and go back to normal idle with no bogging or shuttering of the car. But over the last week besides it doing the same thing it is actually stalling quite oftem when i come to a stop. It doesnt give me any problems once im running just at stopping.

Heres a list of what i have tried:
Did complete tune up, plugs wires etc
Changed fuel filter
Changed oil and oil filter of course.
Also changed air filter.
Even dumped a bottle of injector, fuel and system cleaner into the gas tank.

Ive also picked up the haynes repair manual hoping it would help because im not very vehicle friendly when it comes to fixing or dignosing problems. 2 of my buddies said they believe more than likely its going to be a gummed up throttle body or IAC. Now heres where I am made out to look like a fool since im not very car lterate. Even with the manual it doesnt shown too much about the throttle body or how to even get to it or where it is lol. And as far as the (iac) i cant even find a refrence to it in the manual. If you guys can point me in any direction or give me more info id appreciate it. My wife no longer wants to drive it in fear of breaking down and we only have one vehicle. And I dont want to get to the point of what ever the problem may be that the longer it goes on I believe would just cause more damage.


Ty in advance for all your help and support. Please be gentle and try not to laugh or put me down like i said i am very new to car repair

Could be a MAF sensor or a TPS sensor goin bad.