Bad IPR coil? Had one that would start and run as no issue. Stop truck and for just 15 mins and it would restart. Try to start after 30 mins and truck would not start. Had to wait till the engine as pretty much cool. Then it would restart.
Leaking oil orings around the injectors will drain down HPOP oil standing around the injectors. When you go to start the truck the HPOP has to fill the oil chambers around the injectors with oil first to build up the high pressure and the engine would stumble for a moment. For me this would happen when the truck sat overnight for the morning start, especially if I towed the previous day. Using the truck during the day was not enough time for the oil to drain down. You can test for leaking by attaching a hose to the HPOP ports in the head. Wire the hoses in a vertical position and fill each hose to the very top. Check the level in the hoses after a few hours. Low oil level in hose signals that head has a leaking injector.