Blue99 is also right, although IPR and ICP issues will usually cause the truck to run poorly but can also affect starting. IPR valves are usually pretty solid, Check the IPR wiring harness (back of HPOP, and towards the bottom), and the ICP harness will sometimes get covered in oil and will need to be cleaned or even replaced. That's an easy connector to find, but the IPR harness is tougher, uses te same connector as our injector harnesses though so you could pilfer it from one of those.