My buddy has a 2002 f250 5.4 and there is oil leaking into the hole where the plugs go. It fills up and shorts out the plugs to it misfires for that cylinder. Any have this issue ?? Hard to see where the leak is coming from and the valve covers look clean.

 

have only ran across this problem once and it was a hairline crack in the head on # 3 cylinder-i hope that is not the case with your engine.