octaneman

If the ignition coil is suspect then the only way to verify it is by using a spark tester to visually see the spark's intensity, length, strength, and duration. Readings will have to be taken with an ohm meter when the engine is dead cold and then hot to see if the spark is intermittent. Since the flywheel key is ok and nothing is out of place, spin the flywheel and look if there is any evidence of binding, scoring, governor misalignment, or metal to metal contact. Check the air gap and see if it has shifted. if everything checks out, look to the carburetor choke and see if it's working properly. If it's the diaphragm type, the diaphragm sometimes gets stiff and gas leaks into the automatic choke.