I have a 7.3 idi diesel and it's always had a knocking noise. figured it was fuel related and replaced injectors and return lines. The knock has not stopped and today on the highway its was running bad and was smoking white and some blue tent smoke. I am far from a diesel mech but have got to figure this truck out, i've been trying to fix fuel problems for awhile. Does anyone know whats going on with this engine? Thanks