It will stumble and jump up to 1400 rpm & back to 550. It even stumbled and missed all the way up to 2500 rpm's and than would run fine until it idled again. It dosn't always happen and thats what drives me crazy. The first time it happened was about 9 months ago .I seafoamed car and all was well after. also did plugs, wires, o2's and feul filter at that time . Now its back? What do I look for? EGR , IAC, MAP, OPTI, FUEL PRESSURE< CAT CONVERTOR?? woulld a scanner show the problem?

 

Scanning your car would definatley help you isolate the problem.

 

Well I had GM scan the car and no codes came up. They test drove it and no idle problem. I didn't have the problem either for a few days and they think it was either bad gas or dirt in the feul injectors. I drove the car home for about 10 miles without any problems. I stopped and got gas and continued to drive. About 2 minutes from home at a light it starts again. It did it 3 times before I pulled into garage. WTF!!. I think I'll put some dry gas in & see what happens. If it continues I'll clean out egr & IAC. and go from there. Any suggestions??

 

Anyone?

 

I have this same problem!

It is only after the car has been running for a while though!

I ahve no clue what it is.

Itll just jump from 600 to about 1000 or even up to 1300..

Anyone know a solution?