I have an 03 3500 dually with a nv5600 that has started having problems since the weather has turned cold and wet. I have to let it idle for at least a half an hour before I can drive it and the whole time it's idling the RPM fluctuates erratically as dose the speedometer. Also when the roads are wet the truck will just randomly accelerate. I'm wondering if anyone else has had similar issues and if so how did you remedy them any help would be great thanks.

 

Codes? Try resetting the TPS.

 

spend $110 at cummins, and replace the fuel control actuator. easy job. The '03 is an astounding motor, but has a poor computer. the diagnostics side of our computer leaves much to be desired. your throttle issues sound a lot like the ones i had a few years ago. give it a shot...