I have a 2001 Duramax with 123,000 miles. I was towing my boat last week and my service engine soon light came on. I stopped at a gas station and everything seemed to be fine. When I got back on the road, it seemed like my truck lost 50 percent of the horse power. I pressed the gas peddle but it did not respond. I dropped the boat off and the truck went back to normal operation. The service engine soon light stayed on. I have a programmer that I use to add additional horsepower. I reset it back to factory settings and tried to pull my boat again. Same thing happened again. Do I have a bad sensor or is something else going on?

Need to get the codes out of it and dont reprogram it, that will erase the codes.

I took the truck to a mechanic today. He connected his computer and said that it was a mass air flow sensor problem. He replaced the Mass Air Flow sensor which wasn't cheap. The mechanic also replaced the K&N air filter that I had on it with a fram air filter. I picked the truck up and it ran fine. I put the trailer back on and same thing happened again. The service engine soon light came back on. The light goes back off after you drop the trailer off. What else could it be?

Fuel filter.

Same problem I had with my 01. Juice box cured it. No Joke. We call it defueling and it's related to overboost codes and MAF. I don't think GM can fix it. Juice does.