Ebar, yeah I think Pontiac Jim has got this one nailed down with the most likely cause, high floats and or gas sloshing out. as PJ said your hard start, where you thought it was flooded would coincide with that diagnosis.
most likely it is a carbuereter stall and those come in 2 forms "rich stall" or "lean stall." A common "lean Stall" comes when the throttle plates are tight when closed at idle...
but now are open and driving and suddenly slam shut...... this causes an over lean condition, you can see it on the air fuel meter if you use one, but if it is too lean for too long it will stall the car.......so the car manufacturers put on an "anti-stall dashpot", on the side of the carb which is basically a plunger that prevents the throttle from slamming shut.......it eases it down, and does not stall.
Some cars and carbs had them not all it depended on engine and trans combos, also many hot rodders took them off. One way to prevent that lean stall is just a little more opening of the throttle plate at idle, very little. but just enough to prevent the over lean stall.
it it happens again when you come off the gas real suddenly and the throttle slams shut, and no hills involved or hard braking, it could be that. But I think PJ is right, it is a rich or flooded condition most likely.
Vapor lock does not need any rapid deceleration, rather heat alone while driving, will cause the fuel in the suction side of the pump,...between tank and pump ......
to boil and vaporize because the vacumn created by the pumps suction lowers the fuel's boiling point, and today's gasoline already has a low boiling point.
with vapor lock you can be cruising along and the car just stops, no fuel and no hard stop needed. A return line to the tank is the is the cure for vapor lock.
Float height is critical on all carbs, you need that set right before you can deal with anything else, does not sound like you are having it regularly. i would follow PJ's plan check float height and go from there.
and I always recommend a bottle of ................"Redline S1 Complete Fuel System cleaner", drop a bottle in your gas tank when full. It will clean up the carb and intake even remove carbon deposits on the pistons. It contains the only chemical that will do that...PEA... Poly Ether Amine....the trade name is Techron.
It was developed by Chevron Chemists. Redine also has octane boost and upper cylinder lube as carriers for the PEA, so you win all around.
Nothing comes close, it has the most PEA of any of the very few products on the shelf that have PEA......
If it does not have PEA..it is just Voodoo,....others that have it are Amsoil PI, Gumout Regane, (not all Gumouts, only Regane) Techron,.....a couple others.
anyway your car sounds cool! keep driving it! Garage Queens just rot out anyway.....