2004 8.1 workhorse started cutting out when going up a hill. then got to where it would cut out on flat ground. its like turning key off and back on. you can stop and turn ignition off and restart it and it will run OK for awhile then start doing it again. replaced fuel pump and filters before this last trip. took a 400 mile trip and a got a knock sensor light. cleared it and finished the trip. on the way home about 150 miles in the trip check engine light came on again for knock sensor. cleared it and headed on home about another 100 miles is when problem started and no codes. need fixed headed on another trip next month