2001 GMC C2500 Power Loss

2001 GMC C2500
90,000 MILES • V8 • 4WD • AUTOMATIC
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ROBSTEN
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For the last two years I have taken a 1,200 mile 2 1/2 day trip from Arizona to North Dakota pulling a trailer.

The truck has plenty of power and pulls the trailer without much effort from the beginning of the day until about 5 - 6 hours into the trip. I then notice a gradual loss of power and speed over a period of more than an hour. No unusual hills just rolling country. The power degrades to about 40 MPH or so and I have to punch into passing gear to get back to 50 - 60 MPH. Power continues to degrade and hold around 40 MPH.

If I stop for 5 - 10 Min, power comes back and is good for another hour or so. Stop for gas - same thing - power good for another hour or so than degradation again.

Other times the truck is fine. Only happens on long trips after 5 - 6 hours on the road.

No engine code lights, good maint, fuel filters, gas filters, oil filters all good. It is like there is a governor or safety feature that kicks in. What is it???
Feb 22, 2009 at 5:08 PM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.
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