What is your vacuum at idle when the engine is running?

This may sound like stupid advice from waay back, but have you checked that some little rascal haven't shoved a potato up your tailpipe (the car's, that is!)? Another possibility is that your gas tank is under vacuum if the ventilation is clogged, then you should hear a rush of air intake to the tank when you twist off the gas cap just after the engine has died. I'm serious, I have had cars with both those problems myself. Olaf

Might be the idle circuit in the carb.

Can you keep it running by pumping the acclerator or a larger throttle opening?

Grand Wagoneer did similar act way back upon a time. It turned out to be a loose connection to the coil inside a connector clip. Connector looked and seated well. It would cut out at random times. Spent a lot of money on all sorts of parts.

Try starting it up and jiggling various wiring harnesses/connections.

If you've still got points and condensor under the distributor cap , make sure they are good, esp. that condesnor, they can act really weird when they get old. (short out when they are hot, and when they are cool they behave like normal). Fuel filter been changed ??

If it runs for a few seconds then dies, I would start by rebuilding the carb. Pay close attention to the choke and float settings. If that doesn't solve it, start looking for a large vacuum leak. If the engine dies when you open the throttle, it usually does so because the accelerator pump in the carb is not working or because you have a large vacuum leak making the engine lean out and die.

Connector clip?

i believe what kevin is talking about is the copper piece on the inside of the coil wire that hooks onto the coil. also since most of your other parts seem to be okay according to you, and you were able to drive it but once you got onto the throttle a little and it died, it sounds like me and reed could be right about having a bad accelerator pump and or needing a carb rebuild.

Hold the phone up to it, so i can see it...
If you look down the carb, and activate the accelerator pump, does it squirt fuel? Fresh or reasonably fresh, viable fuel. What is the position of the choke flap?

When you pull a plug wire, and create a reasonable gap, and crank the motor, do you have a consistent spark?

Next, I'd use a timing light to rule out a slipped timing chain, and inspect the distributor for a loose bolt.

Then I'd want to look at the spark plugs if not any firing or back firing.

Connector clip?

NO FUEL IS SQUIRTING!