I have been chasing my tail trying to solve the random misfire problem that is so prominent on 4.0L 6 bangers. For me it would happen around 3K rpm. My problem began when I rebuilt the engine. I had it stroked to 4.7. I replaced everything on it including sensors. I had modified the exhaust and fuel system to accommodate the beefy engine. The misfire revealed itself immediately. I tead the forums and tried everything including wrapping injectors and installing heat sheilds between intake and exhaust and another heat shield between the injectors and intake. I had pulled out the harnes and replaced every wire that looked toasty including ALL the pigtails. Still the misfire remained. Scan tool indicated random misfire, shorted ignition coil pack and cam/crank out of sync. I went through a ton of crank and cam sensors. Each time the problem would be improved for a bit but would always come back. I always used what I believed to be quality parts such as NGK, NTK, Standard etc. The would run from 30 to 80 bucks. Finally out of desperation I popped for an OE Mopar sensor at $170. That made all the difference in the world. This engine is a face munching torque monster. If I was running an OE size tire I'm sure it would keep up with mustangs and camaro's.
i wanted to share this because Id never find posts of the misfire being sorted out.
Anyway happy wheelin and stay safe.

 

Which sensor did it ?