We have a 2003 Ford F-250 Powerstroke Diesel. While my boyfriend was driving to work around 4:30am, it shut off while driving. (And would not come back on.) He changed the CPS, and he also noticed that the starter came loose and he had to screw it back in. It started and drove the rest of the day fine. The next morning at about the same time while driving to work, it did the same thing. He ended up just hitting the starter and it finally turned over and is running again. Any suggestions as to what could be the problem?