Everyone ... I know this issue has happened before and I am sure there is a solution on this forum somewhere but I have been looking for several days and cant find one so I am posting a new one ... please forgive me

I was driving home about a month ago was going up a hill when I heard a single pop noise and my truck started running rough and the engine light started blinking. I drove straight to AutoZone and by the time I arrived the Engine Light was solidly on (code indicated a misfire on cylinder 6). I had just replaced my Plugs and Wires 8 months ago with Motor Craft wires and Plugs so I disconnected battery for 20 minutes while Swapping the Coil Packs to see if the Misfire would move from Cylinder 6 to Cylinder 7 (code reappeared on Cylinder 6). I disconnected battery for 20 minutes to clear the code again while I changed the Plug Wires again and the issue seemed to away for a day then the code reappeared on cylinder 6

Just as preventive maintenance I had done the following (listed below) about 6 months ago ...

Changed Plugs (used Dielectric Grease)
Changed Wires (used Dielectric Grease)
Cleaned Mass Air Flow Sensor
Cleaned Idle Air Control Valve
Cleaned Throttle Body
Clean Intake Air Temperature Sensor
Cleaned EGR Ports on Throttle Body Intake

my truck has 220,000 miles and runs as strong as the day I bought it up until this issue .. any ideas as to what may be causing the problem ... one other note is that when I pulled the plug for cylinder 6 I noticed that it was covered in fuel so I didn't think it was the fuel Injector ... I am leaning more towards a spark issue in the cylinder ... if I am on the wrong track somebody please let me know ... thanks in advance