HELP!!! Truck won't start!
 

96 f350, manual tranny wont start
K guys, new to the forum... Have a 96 f350 with 250k miles and I can't get it back on. Truck was driving fine, hit a bump and it lost all its engine power and cel came on. Truck stayed on but just felt really weak, when I got home it didn't want to shut off, so I popped the clutch in gear and turned off. You could see very dim that the cel was still on. The alarm didn't want to work either. Came back the next day and it wouldn't turn on but cel was gone and alarm worked.

So this is the list of stuff I've done:
Changed cps, changed ipr, changed hpop, changed harness to ipr, changed icp, changed idm, changed injector rings, changed pcm, by the way pcm had a chip, removed that too, changed glow plug relay and glow plugs and truck still won't turn on. Tired of wasting money and my question is how does the ipr get ground, when key is off it has ground and when I put it in the on position there's no ground, cranks perfect and for a long time but no start. Any help is greatly appreciated... Thanks in advance. Oh it's throwing a back pressure sensor code, that's the only code...