I got a clue that might be happening b/c I noticed a slight electrical shock when touching that particular wire with the engine running. I'm not sure how to go about measuring the resistance pathways with the coil on plug design, but there must be a similar way. One more idea, there's a small oil leak from the valve cover that just happens to be dripping on the spark plug.So I assume, to eliminate these possibilities, I do a compression and spark test?
Yes, that would be a good place to start.