[rpmerf]

Intuition tells me either fuel pump or coil. Both of them will get worse when hot when they are failing.

Some thoughts:
How do the plugs look?
If you take the air filter off and open the throttle, do you see the accelerator pump spray gas? Does it happen after it dies?

The hard part here is you stay it happens with the vehicle in motion. Can you have the vehicle in drive, foot on the brake, hit the gas a bit to put load on it and have it die? If so, to test spark, you can try putting the timing light on a plug wire and see if it stops sparking as soon as it gets a load on it. Try it with a couple different wires. For fuel, you can try squirting some fuel in the carb when it starts to die. Can use starting fluid (in a spray can, so this might be safest), dropper, or a bottle. Might be able to use carb cleaner. If spraying fuel makes it come to life, it is a fuel issue.