Won't Start and has no oil pressure after replacing HP

[JC Souders]

I replaced the EGR cooler due to internal leak. The truck then started and ran for an hour and a half no problems. The next morning started and ran till warm then started to drive, BOOM stall. The Scan tool showed loss of oil pressure. Back in the shop I tested low pressure oil during crank and have 10 lbs. Only 16 lbs oil pressure on HP side. Checked and found no oil leaks on high side. Replaced the HP oil pump, still no oil pressure. I feel that I am a decent mechanic but what the heck am I missing?

[JC Souders]

Change. The Low pressure OIl is almost 85 lbs and zero at IPC.

[JC Souders]

Okay I got it going. Tiny piece of the other HP pump in the IPR. Now the question is why do I have a High idle cold or warm. Never seen this before.