6.0 no start after egr delete/oil cooler replace.

[motox tech]

I have an 03 6 litre, 150,000. Did Egr delete, and replaced oil cooler and o-rings. started right up and ran rough for 30 seconds or so, like it was purging air from fuel, then died. Have nothing now. Have cranked and cranked and cranked, and no smoke. oil gauge is reading pressure about midway on guage when cranking. local mechanic hooked to computer and have 400 kpa on oil pressure reading, with no other codes. he said that was not enough . i know nothing about this system, other than things ive read online. is wifes truck and need help fast, anything apreciated. thanx