Vintage Cars: 1965 Pontiac 2+2 cutting out (no spark), running down the road, intermittent problem

Question
I have a 1965 Pontiac 2+2 convertible, and have an intermittent problem I
can’t get to the bottom of. The car runs very strong and starts with no
problem. But every so often the car just dies (like the ignition switch is turned
off). It happens sometimes when idling, it happens sometimes when running
down the road, just whenever it feels like. If I set for about 10 minutes it
starts right up and will run great, sometime for days sometime for 5 miles. I
checked and when the car dies there is no spark. I have replaced the battery,
the starter motor and solenoid, the ignition switch, the coil, and the
condenser, the spark plug wiring including the coil to distributor wire. Has
anyone ever experienced anything like this happening? I am at a loss and in
the need of help. Thanks!

Answer
Electronics isn't my strong suit, but I think there is an interaction between the alternator and the ignition.  HaVe you checked to see if the alternator is doing something?

You don't mention points, does your car still have points?  have you inspected them and the rubbing block?  If you have an aftermarket electronic ignition, then you may want to replace that since this kind of failure is something that happens to that type of device (and the alternator).

Don