I have a 2002 Sierraa 1500 with the 4.8 engine with 120,000 miles. I have been expereancing rough idle and increase reveing when temps get below 50 degrees. After a short time and the engines warms the truck runs great.
I have replaced the air intake sensor, the coolant sensor, new fuel filter, plugs, removed and cleaned oxegen senors and cleaned the throttle body but none of these has worked. Please help. Thanks

 

If you have replaced the IAT then you mean you have the replaced the whole Mass Air Sensor? When you cleaned the throttle body did you take it off or leave it on and just spray it? If you take it off you can inspect the IAC valve and lots of times it will gum up and get sticky.

 

Sounds like what my 97 did when the crank sensor went out.....I would check it too

 

Thanks for your help and will look into both suggestions

 

You may want to check your fuel pressure regulator, my son's truck had the exact symptoms you are talking about. Here's our post from this month.

https://www.truckforums.com/forum/sh...ad.php?t=15197