[blazes9395]

As said, for sure check for codes, get a good scanner on it and see what it is doing. Does the truck run fine for the first few minutes, then after that the problem starts acting up? If this is the case, take a good look at the oxygen sensors. Is it missing, when you say it rocks, is it missing, or bucking when driving? If this is the case, again you need a competent mechanic to diagnose it, but a good scanenr should be able to pick up whats going on and kind of guide you from there. Good Luck!