WILL NOT HOLD IDLE UNTIL IT WARMS UP

[Huntintruck]

2000 GMC TRUCK SIERRA 1500 4WD

8 Cylinders 294 V 4.8L SFI

 

WILL NOT HOLD IDLE UNTIL IT WARMS UP

 

Truck seems to run fine, but check engine light is on. My mechanic checked for codes, but said there were no codes and turned the light off. I have had no problems cranking, until the last few mornings have been below 45 or maybe 40 degrees. The engine cranks, but goes dead. I give it some peddle, and it runs, but goes dead immediately when I let off the peddle. I can hold the peddle for a minute or so, and it warms up enough to run normal, and the check engine light goes off. It comes back on within a few miles. This morning was warmer, about 60 degrees, and it started and idled perfectly. I am going to check the codes again, but just wanted to see anyone has run into this.

 

Thanks!

[Supercop8100]

Throttle position sensor going bad. It runs after its warm because the temperature difference makes the pcm compensate for lack of throttle.

 

[bartlanz]

I would also check your cap, rotator, wires and plugs (if ur truck has them). I know on my 98 when it starts doing that it is a harbenger that i need to replace my cap and rotator

[97chevy350]

Those sound about right, but you might also check your idle air control.