The last sentence may be the key to your answer – when it cools down it has spark. This typically correlates to a broken or worn wire in the windings of the stator. Testing a stator can be extremely difficult, and getting correct ohm readings can be almost impossible sometimes. The other potential trouble items are easier to test. Be sure to check the key, tether, trigger, and coil. Then move to stator replacement if those all test OK. – Jason Houle, Straightline Performance