Help with a miss and voltage drop

I had a problem with my car doing that. The igition coil was arcing from the high side to the 12v side. My old plug wire set had allowed one ot two of the rubber boots to be pushed down on the plug porcelain but the actual metal that grips the plug was not touching. So it would jump that gap internally but once in a while it wouldnt and the high output coil voltage would find a spot that was easier...and it was right at the coil. Tfi setup and highoutput accel coil. Hot spark!