Q - I have a 2003 6.0 I was driving down the highway and it died on me. I got it to a shop and they said my ipr screen and low pressure pump was bad, so they replaced it still no start. So they went on to pulling the valve covers nothing wrong there they said. So now my truck sits in my driveway torn apart and I don't know what could be my problem.

A- If the IPR screen was bad or had debris in it there is a good possibility the IPR or high pressure oil pump is bad as well.  I would check and see if the truck is making high pressure oil above 500 PSI when cranking.  If the low pressure oil supply is fine after they replaced the low pressure pump and you don't have 500 PSI, odds are the pump or IPR regulator has gone out.