CRUISING DOWN TH ROAD AT 50 OR MORE, THERE IS A BUMP IN THE PEDAL. THEN THE TRUCK SLOWES TO 30-35. PUT IT INTO NEUTRAL, REV IT A BIT AND IT MIGHT START RUNNING CORRECTLY. I HAVE REPLACED THE LIFT PUMP 2 TIMES, CHECK FOR AIR LEAKS, NEW FILTER AND LINE INTO THE TANK. SHOWS CODE OF 216. ANY THOUGHTS