Found out my truck had #4 injector replaced before I bought it. Had really rough start like only running on 4 cylinders. Had to let it warm up for at least 30 minutes. While driving it would lug real bad and miss under heavy throttle. Got to talking to people and they said sounds like air in high pressure oil system. I pulled the left valve cover and started checking stuff out. Found stand pipe for oil rail not seated properly. Reinstalled correctly and put back together. Ran it and missed for about a mile. Cleared up and starts and drives fine now. Glad it's good now been driving me crazy trying to figure it out for the last few months. :scuffy