Here is my situation, was hauling hourse trailer from missouri to kentuckey i was making about 45 psi on boost and pulling hard on the hills it was running really good. then it just would not pull as hard it would not even light the bottom turbo just sit there at about 25 psi on boost no smoke. it was almost like it was not fueling hard anymore. we stayed the night in kentuckey and then in the morning it was all good for about 40 min then it started not fueling hard again it will only do it when it is really hot after u have run it for a while. if you let it idel why u eat lunch and then come back to it after it has cooled a little it will be ok for about 5-10 min could the relief valve be giving it up when it gets hot under the hood?