2000 Sierra Rough Idle When Cold

[Kelsey92504]

I have a 2000 Sierra with a 4.8L and when its cold the first start of the day it starts up and idles high when you first start it like it supposed to and then once it warms up a little bit and idles down it acts like it wants to stall or rough idle. Less than a year ago I had the fuel system serviced and they burned all the carbon out of the motor, and I just changed the fuel filter. I was going to change the plugs and wires but I talked to another guy with the same truck and motor he was having the same problem and he said he changed his plugs,wires and fuel filter and he still had the problem. I have no engine light or code. My buddy says he is almost 100% positive it is the temp sensor. Does the 4.8L have 1 or 2 temp sensors? Any help would be greatly appericated. Thank you

[gmtech4]

remove and clean your MAF sensor with brake cleaner and compressed air if you got it,or air dry ,I raised the idle of a truck once by doing that ,easy & quick to ,try that

[Kelsey92504]

remove and clean your MAF sensor with brake cleaner and compressed air if you got it,or air dry ,I raised the idle of a truck once by doing that ,easy & quick to ,try that

 

I checked and observed the maf and the throttle body and both were spic and span clean. Another guy told me to clean the Iac and that could be it. Thanks for your help in advance.

[mtm700]

If that don't work, the intake gaskets may be leaking. I have had a few in that did not set any DTC's.

[Fortune50]

If that don't work, the intake gaskets may be leaking. I have had a few in that did not set any DTC's.

The upper manifold or lower manifold gaskets?

[minibike132]

+1 on the intake gaskets

[minibike132]

The upper manifold or lower manifold gaskets?

 

There isn't a lower intake on this motor.