Simplicity Sunstar 18 h.p. tractor with mower deck. Hydro works nice - has little or no creep. Power steering works great. I recently had the mower deck off, cleaned, wire wheeled, primer'd, painted, sharpened the blades, and greased. Deck is solid - no rust or holes. Deck raises and lowers smoothly. Cuts really nice - see pic's. Tractor starts immediately and runs well at slower RPM. Tractor has plenty of power to cut tall grass even at 1/2 motor speed. When running at high RPM, motor has a miss. When I pull the plug wire off on the Right side, motor will stay running. If I pull the plug wire off on the Left side, motor will stall. Compression is even on both sides. Tractor runs and cuts grass fine at slower RPM. I have the mower deck covers. We adjusted the carb and put in new spark plugs. Not sure what the issue is????