And I had the P0219 a&b before I started, is never figured it out, I had the P0300, and I just started getting the P0521 right before the rebuild but I didn't have time to address it yet and thought it might be from the AFM since it has the high pressure oil pump, guess not. The crazy thing is that after tearing that motor down and rebuilding it, it is doing the exact same thing that it was before the rebuild to cause me to rebuild. I have new lifters, trays, springs, seals, cam, can sprocket,, non AFM cover plate.fuel injectors, wires, coils, timing plate, cam sensor, oiI pump ,oil,, oil filter, antifreeze and gaskets, all the way down to the block. I wondered if I caused a problem making a mistake when I did the lifters but I was meticulous with this project and asked a lot of questions of the AMS Racing rep pertaining to the new stuff. I know that I did everything correctly so unless this all gets solved with a tune (I doubt) or in back to square 1. I leave in 4 days to go to California for 3 weeks for work. I need to drive this. I actually considered swapping the motor out of my 05 Tahoe LT, it's a 5.3 but the trans is trash. The motor runs like a top. I'm a glutton for punishment huh? That's again for the help guys