I have a 2004 expy with 230k on it 5.4 I have a misfire code on #7. I thought I would change all the plugs and coils. I took the drivers side front coil out and couldn't budge the plug. Am I in trouble? Are these the ones that break or strip out? Then I noticed my heater control valve leaking, on the passenger side of the engine. That is probably causing the misfire, I ordered the valve. I still want to change all the plugs and coils. Any advice ???

 

The plug problem started in year 2004 . Best to confirm with Ford.