Small Engine Troubleshooting Problems? Ask a Mechanic Now.
I see question is still open! If it were mine, I would run a cylinder balance test. Loosen the spark lug wires, and with engine idling, remove one wire at a time, engine should continue to run. If engine dies when one wire is removed, the opposite cylinder is not firing. Check it for spark. If it has spark, swap the fule injectors between cylinders and see if problem changes cylinders. If it stays at same cylinder, cylinder has problem maybe compression or valves. If it changes places, replace the fuel injector.