2007 Liberty with a 3.7. Check engine light has been coming on for the last 6 months. Misfire in cylinder 6. I have put in new plugs twice, purged injectors, new coil and had carbon cleaned from engine and light still comes back on. what could be causing the misfre?

Had same problem with #2 and ended up being a valve seat had to take head off get a valve job and machine

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2003 jeep Liberty Sport 4x4
2.5" lift
255/70/16 AT


Nick