popping out of exhaust miss
 

OK I have a 92w250 that I installed a 95 p pump engine out of a f700 medium duty truck a 190 HP pump completely rebuilt engine .20 mahe pistons with marine bowls, new colt cam stage 3 with 24 valve lifters, head studs .10 head gasket , 4k govoner spring in pump , 0 fue plate 200 HP injectors timing set at 18 degrees pump was rebuilt 220 fass installed head was redone with new guides,seals and seats the problem I'm having is the truck has a popping sound miss out of the exhaust you can see the truck shake it does it bad when cold when its hot its noticable but not nearly bad already replaced overflow valve and injectors no help don't have fuel pressure gauge hooked up yet could this be a fuel issue still? I pinched off the return line with no help I have thought about valve issues but I just had the head reworked ? Any advise