UFCuDid you check the false bulkhead. It is the connection on the ECM box. My 98 xj8 had the same intermittent starting failure. It didn't look bad until I took the cables off and then could see that it was arcing and the plastic was partially melted. I would have never found it but not from the suggestion of sparkenzap.

My apologies I thought I was on the X308 site. It can be the same problem. Look inside the box and you can see where the false bulkhead is. It's where the main cable comes through the side of the box on the left side of the box.