I am working on my partner's 2007 F250, it was running great, and we did an aftermarket EGR cooler, and a new oil cooler, and of course the screen was torn in the old one, tore it all down, cleaned everything, put it all back together.......with the new parts, and no start, we cranked and cranked and cranked on it, for about 20 to 30 seconds at a time, giving it 3 to 5 minutes cool off time for the starter between cranking, about 30 times over a two day period, and no start. Finally, I decided to give it a little starting fluid, and it finally kicked off, it would run at a higher RPM, and if you so much as let off the throttle a fraction of an inch it would die, and not start again without starting fluid. I got it running again with the fluid, it was at 2000 RPM, and my mechanic reached over and turned on the A/C (we are in Florida) and it died. I have no way to check the HPOP pressure, but the truck was running great before we did this, and I checked it for codes, there are none! It will not start without the starting fluid. The longest we had it running was about three minutes, then his foot slipped back just a hair on the throttle, and it died. The truck only has 117K miles on it.

 

Did you disconnect any grounds when you performed the worked? There is a ground on the intake out back near the ficm.
It would help if you can see the ipr duty cycle and ipc with a fancy diagnostic tool. But there is a way to check the icp with a volt meter, and calculate what the high oil pressure is roughly.
But check the ground first though and I'll help here on

 

Thanks, I will check that right now