You should check the fuel pressure and run a can or 2 of good fuel system cleaner. BG44K is the only cleaner that really works. You hjave to go to a car dealership parts counter to get it and it costs $20 a can. Run one can per tank of gas. You will then run a third tnak without. You may find that there are changes in performance while running the cleaner as carbon and sludge deposits are removed and worked out of the engine. This will clear up by the end of the thrid tank if having a dirty fuel system is the issue. Even if it is not if you have never ran a fuel system cleaner in your truck it is time to do so and will help performance and gas mileage.
I am also giving you a walk through diagnostic for your situation. Just use the link below to find your way to the diagnostic;
Saturday, November 10th, 2012 AT 1:17 AM