Ok My husband just bought a 01 F350. had issues with rough idle got a guy to run a diagnostic on it he said #7 and #8 injectors were bad. replaced them with used (can't afford new right now) Well still having issues had diagnostic ran again and said #7 was bad. put injector out of number 7 in number 5 and now it works. still does not seem rigth have checked all electrical connections and are getting power. with engine running he unplugged the injector in cylinder 7 slight difference in idle but not as much as any of the other injectors. Any suggestions as to what might be the problem? Let me also mention that the truck sat for a time before my husband bought it. I don't know how long but the guy charged the batteries and it started right up. We have also changed all the glow plugs and tested the glow plug relay. The guy that ran the diagnostic did not clear out the computer he said after we firgured out if the injector was bad to bring it to him and he would clear it out Please any suggestions????