Exact same thing happened on my 67 Fastback. After much consternation, it
turned out to be the ignition module inside my new Mallory distributor. When
I checked it in my driveway using the Mallory diagnostic check, it checked
fine, when it heated up after driving, it didn't. Change the module (not
cheap) and it should be fine.

-Scott

"Nevada Larry" > wrote in message
...
> My 66 Mustang quits running after about 5 or 10 minutes. If I am driving
> down the road it restarts and works fine after that. If it happens at a
> stop sign, I have to restart it. It starts immediately and works fine
after
> that. If I park it for a while and start it again the same thing happens.
> New wiring harness and ignition switch 4 years ago. Mallory electronic
> distributor and new Pertronix coil. Fuel flow and spark are good. 289 4V
> with C4 automatic. What should I check next? I hate intermittent
problems.
> Have lost all faith in this car. Purchased in 1992 and has been great up
to
> now.
>
>