I have a JD riding mower that is approx 7 years old. Ran mower today and engine was cycling up and down when cutting grass, almost to the point of killing. Disengaged blade and it continued to cycle. Turned mower off and tried to restart, all it does is turn over. I removed plug and cleaned it, checked for fire, which is OK and reinstalled plug. Still would not start. Sprayed starting fluid in air intake and still would not start. I removed plug again and it was wet with gas. Has gas and fire but won't start. I am confused.