your getting a bad signal between the ecm and the pedal position sensor
the pedal position sensor wiring could be damaged but most likely the sensor is bad.
when you turn on the ignition you should hear the throttle body calibrate itself during the self check and if it and the pedal position sensor are within tolerances it should pass the check and allow you to start the engine without error.
if your clearing the code and it runs ok for a while and then errors out there is a high chance the wiper inside the pedal sensor is worn.
the best way to check this is to plug in the pc diagnostic program and monitor the pedal signal. If the truck has an obd plug on the harness you can get an obd scanner and maybe do the same.