Bad ground wire?
 

Have been battling a bad misfire in my 00 xj. When you start it up and let it get to temp it starts to misfire and eventually shuts off. If you try and drive it right away it misfires and carrys on. I've narrowed it down to electrical after ruling out all mechanical possibilities. Today we found that pin 6 of the first plug to the pcm had 8 ohms on it. Per the wiring diagram it is a ground wire. Could this be my isssue?