About a year ago my dad bought a 6.5 that the rod bolts came loose on and came apart, so we got a 6.2 with 1200 miles on it and swapped exh. manifold, intake ect.. it seemed to be having trouble gaining RPMs (laboring). I finally changed out the injectors and put the 6.5 ones in about 3 months after and timed the IP with minimal results. a couple of days ago it started running rough like he was losing an injector, i did an inj cut out test with GMTD and couldnt pin point it. any ideas? BTW PMD relocated and swapped with mine for diag purpose, straight piped, OPS bypass