I really need help. I have a 95 turf tracer with a kohler command pro gas engine. It runs great for about 20 minutes cutting, then will all of a sudden start to misfire, it will gradually slow the engine down and usually will just shut off unless i shut the deck off and get it to the trailer quick. Here is what i have done so far, new battery, new stator, new stator regulator, new flywheel, 2 new coils, 2 new plugs, new ignition switch, all kohler and exmark parts. I have good fuel and cold compression. Seems like it might be heat related possibly ?? Usally after it sits for a day or two it fires up, runs perfect for 20 min, then repeats the problem. Sometimes though, even if i shut it off and don't use it for a few days when i go to start it, it miss fires. Any suggestions ?