08 6.4 misfire cyl #5

[cp diesel]

i have a 2008 6.4 F450. it is misfiring on cylinder 5 every 4th or 5th time around. every time it misfires it pops back through the intake. injector is new and rocker arm assembly has been removed/inspected and ok. pushrods are ok. relative compression is good. cranked engine with valve cover off and valve train moves properly while cranking. once started it will misfire randomly only on cyl #5 and like i said it pops back through intake each time it misfires. no codes. passes all test on IDS except i see it misfire on the powerbalance screen. HELP....... oil is not foaming.....