So today I was cleaning up my YJ and checking fluid levels since I hadn't in a few months and something caught my eye under the hood. The center of my distributor cap had a radial hole around the spark plug, when I touched it the whole center plug/cap nipple came off.
I just got this YJ back in March '12 and did a tune up replacing the cap, rotor, and plugs. Anyhow I ran out and got a new coil and cap. Upon taking the cap off I found the tip of the coil was snapped off and a half dozen fried stink bugs in there.
Is it possible that the little bastards got in there and short circuited the cap? I was wondering why for the past month or so it felt like my 2.5L had less balls than earlier this year. I was having really poor throttle response and instead of getting 17-18mpg I was getting 14mpg, but I thought it was due to letting it warm up in the colder weather. After replacing the coil and cap she's running strong again.
Notice how a broken piece of coil is on the left of the stink bug pile.
Fried coil & cap.