The truck is a 2003 GMC dually. It is bone stock right down to the wheels. Tires are 245/75R 16.

I purchased the truck used with 60k miles on it. It ran well and pulled the trailer well.

I had the injectors replaced about 3 years ago. That cost a pretty penny, after I found it should have been covered under warrenty.

When I got the truck back from the dealer, who is now long gone, the truck never had the power it had prior to the injector replacement. The tech/mechanic went for several rides with me with the GM scanner. According to him the truckwas fine.

I was told the truck was "flashed" after the injectors. I do not know for sure. The dealer went out of business before I could ask.

Last year I went on vacation and was pulling about a 4-5% grade. I was down to 40 mph. That was enough.

While on vacation I spoke with anyone who would talk to me about diesels.

Most that pulled large trailers had some sort of chip in their truck. Some had switchable on the dash others just flashed the existing computer.

I went with the re=flash the computer route. I went with Power up Diesel. I installed the 80 hp and everything worked fine. Until my last trip.

I just spoke with a GM diesel gearhead. He told me the 2003 GM Allision transmissions were light in the torque converter, and if the converter had any slippage it would trip off the 0735 code, and go into "limp" mode.

That makes sense.

He suggested installing a new H.D. converter, and future problems would be gone.

He also suggested that I downshift sooner and not let the trans downshift on its own.

I always tow in the "tow" mode. On level ground I do tow in O.D. with the RPM's at around 2,000 at 60 mph.

When I hit a hill and the truck starts to load I will take it out of OD by pushing the button.

I appreciate the help and advise.

Andy