Have a JD 525 with a Kawasaki PA540a engine. When its cold there is no miss, shortly after as it worms up it starts to miss. The miss is more prevalent at high rpms and no load. At idle it doesn't miss as much as you increase throttle to about 1/2 the rpms will cut back, miss/ smoke, as rpm is increased the miss stay up to full throttle. As you can guess plugs foul rapidly.... Now what I have done....... Coil Tested OK but I didn't trust so was replaced and gap set to 12thou and tried 10 thou no change, plug boot tests 5.8Ohms OK, Plugs be replaced and gapped with oem plugs, compression is 90lbs min allowance is 71 so well over, leak down test was 8.5% cold, valves checked at 6 thou... good...., replaced carb with brand new, and fuel pump brand new. also new gas and tank was checked and cleaned All wire look good as well....... Starting to run out of ideas...... was pulling the flywheel next to replace key just in case and was wondering about replacing that little silver ignition module........ Any Ideas would be great thanks....