I have an older ferris 3 wheel rider that all of a sudden has lost power. This is a kohler engine. Starts fine but no power to go up hills or when pto in engaged the engine dies. I have spark on both sides. When engine is running if I take off the left side plug wire the engine keeps running, when I take off the right side plug wire the engine dies. I'm thinking I have a problem with the left side coil wire. Does that sound right.