When I pull my utility trailer with a heavy load up steep hills the truck continues to lose power unless you keep your foot in it. It ends up shifting all the way to low. After I reach the top of the hill it has no power. I turn it off and something resets under the hood, it sounds like a door opens or closes, then it runs perfect until the next hill. I took it to a dealer in Casper WY and the replaced the fuel pump. This did not fix the problem ($784 later). It runs fine most of the time, but sometimes when I turn it off and restart it soon after shutting it off it hesitates for a while even without a heavy load. They said it had several codes like the MAP sensor, Cat back pressure but they all clear after you turn it off and then restart.