I need help asap international dt466 issues

I have a 2005 dt466 international truck came in for service and we changed oil and all filters truck ran great for a 100 miles and then starting losing power and then completely shut down. tried to crank it back up and wont build up oil pressure so we had it towed back in to our fleet and we then replaced high pressure oil pump with a brand new irp valve, and also a new turbo, after replacing with a the old high pressure oil pump with new pump the truck cranked with a extremely hard start , it ran for minute and then shut it self back off will only build up 5 lbs oil pressure while trying to start. let it set 3 hours and will start up and run for a couple min(not even reaching operating temp) then shuts back off.... HELP I HAVE WASTED SEVERAL MAN HOURS AND CAN NOT FIGURE THIS OUT

I need help asap international dt466 issues