My Kohler command 20hp seems to be running on only 1 cylinder. If I disconnect 1 plug wire there is no change in performance. If I disconnect the other plug wire the mower will not start. There is spark on both plugs and I have connected a timing light to both plug wires and am getting what appears to be a good strobe. Is it possible that one of the ignition modules good be bad and still be putting out spark? Any ideas would be appreciated.