2000 THrowing a Misfire # 6 code

[97fordrunner]

What would cause a misfire on a cylinder, I just did plugs and wires and O2 sensors and am running out of ideas. Today I checked for Vacuum leaks and couldn't find any way with the ether method. Any Ideas fellas.
THanks

 

[riverjig]

what was the end result? im having s similar issue but the first time it was a faulty spark plug wire.

 

[backroad101]

Curious too. Add this issue too. Replaced with a plug that still had some life in it. Worked for a while then issue resurfaced and just replaced with a new plug. Seemed to have worked so far but not positive. The truck has been sitting for 3 weeks waiting for me to get time to get it in the shop for the "overheating" issue