[Edbo]

Dennis,
From your description I'd say something in the ignition system is getting hot. Not really the engine.
You have three things it can be; the pickup in the distributor, the electronic module, or the coil.
The only effective way to isolate it would be to replace each item, one at a time until the problem does not occur.
You can test the coil after the spark dies by applying 12 volts to the coil + terminal and grounding the - terminal for a second, just tap it on a ground. Whenever you tap the - to ground the coil will make a spark, if the coil is OK.

Make sure you have the ballast resistor wired in the circuit as shown on the diagram. You MAY damage the module if the resistor is not in the circuit during 'run'.

Ed