Hello, I am new to this forum and also new to the GM Truck.
Bought band new in October 07, have had nothing but grief with this truck.
Can someone please help:

Truck has had loss of power, bucking, jerking. Taken it to 6 different GM dealers, no codes show up at all. Yesterday check engine light came on, drove back 180 miles to dealership, started truck in morning light was still on, got to dealership shut truck off, drove in garage, no light on, no codes nothing.

Loss of power, bucking, jerking, upon acceleration?????
When truck goes into reduced power mode, we accelerate hard to bring speed up, then the regneration light comes on to clean DPF filter.

Why are there no codes showing???? Dealer says nothing wrong, no codes, don't know what to fix.
Anyone please help!!!!!!!!
Sensors??????? which ones?????