help

[danberg1]

i havea 1996 ford powerstoke 7.3 with 237000 miles did a buzz test all eight passed then did a cylinder contrbution test came out with code po 281 po 272 po 269 that means cylinder 3'4'7 its saying contrbution or balance malfition where do i look now and do i have bad injectiors a litttle history when u frist start it up its runs loping rough for a littlr while after you let run for 30 mins it clears up runs like a champ a lillte idle rough i need help please i been looking on all forms its poss bad harness or conctor or ?:confused :