2002 Ford F350 engine won't rev but it starts

OK lets tackle one problem at a time. First the no rev. I must ask does you truck have a throttle cable or not? I am thinking it don't and if it don't there is a test that may need to be done on the gas pedal and on the throttle body motor. Let me know what you find so we can determine what to do.

OK with that there is not much we can do without a scan tool that can be used to read the pedal potentiometers and the throttle body motor. See the way this system works is that there is a throttle body motor this opens the throttle by reading the pedal potentiometers (yes there is two on the top of the gas pedal). Now if they don't read the same then it shuts down the throttle response. It will more then likely be the throttle pedal but there is no test that I can walk you through as it requires a scan tool to test. Let me know how it goes.