I have a 25hp kohler that will intermittently run on one cylinder. The right plug has a weak yellow/blue spark. The front cylinder has a white and purple spark. Can this be caused by the spark advance module or does that problem have other symptoms? Any other suggestions? BTw I unplugged the ground wire (white) in the wiring harness and this did not improve the spark. I had been told to do this to make sure the safety switches weren't giving a weak ground somewhere, so that was ruled out.