I was pulling my 10,000 lb. 5th wheel trailer a few days ago. We were about 1 1/2 hrs in the trip when I noticed a loss of pulling power. While going down a hill, I let off the accelerator. Near the bottom of the hill I tried to speed up but found I had no power. The truck slowed to about 25 to 30. I managed to get to the top of the not so steep hill. I stopped and turned off the truck. When I restarted, I had full power. This happened 4 more times in the next 150 miles (3 hrs). I have plans to replace the fuel filter. Codes show P0009, P0380 and P1781. Also I can't seem to find a repair manual for the Duramax. Help