Need Help F250 power problem

[bjd76]

For the second consecutive 100 hr service I changed the spark plugs (spec'd NGK plugs), put everything together and I'm not getting full power (port engine seems to be the problem (again)). Last time I re-gapped and put together and it ran ok. Rechecked all plug - coil connections and re-gapped plugs this time too. Still a problem and with a knock in top right (starboard) cylinder of port engine. Anyone have similar problem or care to offer suggestions? Boat ran fine on Monday before doing 100 hr service today... Changed oil, gear lube, and fuel water filters as well...

[boats.net]

Plugs should be LFR6A-11 and gapped at 0.043"
Check all the wire connections to coils to make all pins in connectors are good and connected ok.