Stroker engine "diesels" after I shut it down

TIming is what burns completely or doesnt, and leaves hot spots or doesnt. The run on isnt because of a spark being produced by the ignition. It's usually a hot spot in the cylinder because of retarded timing, combined with a carburetor that's open too far to get a decent idle speed with no timing. There's enough fuel and air drawn in that the engine can "run on" until the hot spot cools and it can't ignite. If you've ever seen "Uncle Buck"... that car has run on....lol.