I have scag rider with a 17 hp Kawasaki. It would kill while cutting is warm weather. The dealer replaced both coils. Still had same problem. Dealer then cleaned both gas tanks and fuel lines, replaced fuel filter and cut a vent line in the gas caps threads. The problem is fixed, however, the engine vibrates excessively now. It still works and has plenty of power but the vibration is uncomfortableand has me concerned as the engine used to run very smoothly. Any ideas would be appreciated. Also, anyone had any success obtaining service manual for this engine?