My truck started losing power while towing toy hauler. Fuel pump was making strange noise so I installed new pump. Truck ran worse with new pump. Checked ful pressure 32PSI and 42PSI with vacuum line disconnected from regulator. Called a buddy that runs a shop and he said fuel pressure was normal. Truck runs fine at low speeds and no load. Suggestions?

 

Forgot to mention that I also installed new fuel filter,cleaned throttle body, cleaned IAT & MAF sensors. Problem still there. I installed factory tuning and then re-installed performance program. Drove truck to store and problem still there. On the way home truck started to run better, alot better but still nothing like it is supposed to.