Over a period of time, the items previously listed were replaced, and yet the problem persisted. I don't care if the truck gets worse mileage as long as it will run up a hill and pull my trailer. I hope you can help me get my truck fixed.
Herb Maheu Whiteford, MD

A First, you said the truck runs properly when the engine is cold. There is cold-start enrichment when the engine coolant sensor reads low temperature. Sometimes these coolant temp sensors will go bad and give the computer the improper signal based on the engine's temperature. The dealership should be able to check this on its Tech II diagnostic handheld, which gets its data through the diagnostic plug. Next, your troubles are a classic sign of a ground problem. There are about six grounds for the engine management system throughout the engine bay, not including those at the battery, the frame, and the engine block. If you have a ground issue, as the system heats up it creates resistance, which wreaks havoc on the entire ignition and fuel system. The engine management system runs mostly on resistance sensors. If there isn't a perfect ground loop back to the computer, all the data that the computer is receiving isn't accurate. Get your dealership to print out a wiring schematic and locate all the grounds. Track them down and clean and tighten them all to proper specs.

Sorry we don't have a silver bullet to give you. Sometimes you have to step back to basics. Sometimes throwing parts at something just doesn't work, and it can be very expensive. Good luck with your search.

Technical questions for Kevin McClelland can be sent to him at chevyhi@sourceinterlink.com