2004 GMC Envoy cruise control problems

I purchased a 20054 GMC envoy in february and we took our first long distance trip this summer. At interstate speeds on downhill slopes the cruise control bucks continuously, which I consider potentially dangerous. The local dealer told me that this was inherent in the design of the vehicle, and that many others did this also. I have never encountered this with other vehicles that I have owned.

Dt*: the contact stated while exiting the off-ramp of the highway at 20-25MPH, the check engine and reduced power light illuminated and there was a loss of all vehicle power. Although the engine restarted after several attempts, the vehicle was towed to the dealer for inspection. The dealer determined the accelerator sensor needed to be replaced. Afterwards, the loss of power persisted and the accelerator sensor was again replaced by the dealer as well as the computer.