so i was able to find the problem yesterday. are you running an aftermarket fuel setup and (pump,rails,injectors)? because if you are, you may have the lines that go from the fuel pressure regulator and distribution block mixed up. i just had to switch 2 of hem around and bingo, no more problem.
make sure that the line on the nipple of the fuel regulator goes to the return side of the fuel system. lmk if u would like it drawn out for ya if it helps bro