Is that oil fouling or carbon fouling?
Pull one of the wires from a dirty plug and see if it's getting spark. Use a spark plug tester which is a little light bulb with leads on each end to connect between the wire and the plug. If that wire is firing, it will light up.
Or put a screw driver bit in the end of the wire and hold it above a metal part under the hood and see if a spark jumps.
