I have 9 of these trucks. That sounds like it might be the turbo. In these trucks the turbo will stick, so some times it will pull really good...
This truck should pull with that motor and those gears.. The turbos in this motor stick and it sounds like that is what it doing to you! Ask...
It has been my experience with them that it could be an EGR or Turbo. These turbos stick watch your turbo pressure and pyro temp. And if there...