Q: Do I have vapor lock, carb icing, or fuel pump issues?

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I have a 1964 Olds 98 with a 394 V8 4 bbl carburetor. After driving 25 minutes or more when I come to a stop and it is idling it will stall and when I turn the key it will start but then immediately die. After it sits for 30 minutes or more, it will start up and run with no problem for another 30 minutes to an hour, until I come to a stop again. This seems to be more prevalent in cooler temps, <50 degrees to about 35 degrees. Also, seems more prevalent with ethanol blended fuel vs. 110 octane leaded fuel. I've been told it's vapor lock but I wonder if it could be a fuel pump issue or carburetor icing. Your thoughts? Thank you so much.

My car has 68000 miles.
My car has an automatic transmission.

I think more than anything else that the multiple grades of fuel you are using is the primary source of your problem. If you use an unleaded gasoline then use a racing 110 octane leaded gasoline, it creates tons of carbon buildup on spark plug, intake and exhaust valves and intake manifold.

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