Help -
 

I'm the orginal owner of a 1980 Vette, 62,000 miles, all orginal factory parts - nothing has been replaced.
Recently, when I drive 20-30 minutes and turn the engine off, it will not re-start. The ignition acts dead. After it sets 1 -2 hours it starts fine. The engine is not over heating. Battery is good - lights, windows, door locks, etc. still work when it does this and I can jump start it when it does this.
Is there a sensor that shuts down the ignition if it thinks the engine is over heating?
Anybody have any idea what is causing this?