hope some one can help with this. i've been experiencing a miss on my 1997 j90 spl. I replaced a coil and it went away. Ran good for a day or so, but then the problem came back, got worse, and then the engine quit and won't start. when it was running fast, I heard a clatter that sounded like a ground fault but I couldn't track it down. I suspect a short followed by a power pack failure. Am I on the right track?