Originally Posted by Frankie the Fink

Well -- its clearly an intermittent electrical problem...could be ignition circuitry or main circuits passing through the bulkhead. Its pretty easy for a bulkhead connector to get pushed in and not make contact. My '63 had an intermittent issue in this regard.

One way to isolate the problem is to take your next drive with the headlights on; if you have the problem and the headlights blink out its a main power connection; if they stray on it could well be ignition.