I noticed a sweet little bolt o' lightning jumping from the top of my #5 plug boot to the block today. Probably not a good thing. This could be *the* reason the XJ has been running so poorly, or it could be *one* of the reasons it's rough. Pre-HO Renix 4.0, btw. After restarting, the spark was not jumping anymore.

Time to buy new plug wires, or could there be something else wrong, too?