1988 Mercruiser 454 I/O misses when reaches operating temp. Engine was running fine but began to miss after running at cruise speed for a few minutes. Found the coil was visibly arcing from center output terminal down the sides of coil tower to both primary posts. Suspected bad coil, so I replaced it. New coil seemed to fix problem until warmed up, then miss returned. Although no arcing is now visible along the coil tower, placing a screwdriver tip at the bottom of the rubber insulator boot causes a visible arcing that jumps from the coil to the screwdriver, then to the primary terminal post. Any experience with this problem or ideas about how to fix it would be appreciated.
