Lately now that its getting cold, i start my 02 GMC Sierra and it idles extremely high when it first starts then idles to the point where its about to turn right off. It continues this high and low idling till im driving for about 20 minutes. At stoplights the truck does the same and when it idles low it dims the daytime running lights as well as the speedometer lights, Any ideas?

Thanks in advance

 

What year is it?

 

Intake gaskets. Any trouble codes yet?

 

Is anything done to it? I had a similar problem but it was tune related.

 

The truck is an 2002, and im not to savvy with the codes, i took it to Autozone and the guy said it was the MAF sensor. Could this also relate to my idling problem. Yes i sent it in to Wait4Me Tunes about 2-3 yrs ago, that have anything to do with it? I have an intake and exhaust on the truck Thanks again.

 

Might try cleaning the MAF. Sometimes if the sensor gets dirty you can clean it and everything is good.

 

I still say intake gaskets. It probly says MAF sensor on that autozone printout because the truck is running lean. The actual trouble code would be helpful though.

 

p0171/ p0300

 

Clean the maf and check for any vacuum leaks using carb cleaner.

 

Good idea...might as well clean the throttle body too while you're in there...