Take the gas cap off for a few minutes and see if that makes a difference. Could be stopped up enough now that it is letting the fuel pump create a vacuum on the gas tank. If so then with the cap off it should continue to run.
Another thing may be the coil getting too hot. How long does it have to set before it will restart and run?
When it acts like this check the spark to the plugs to see if it's bright blue. If not then something is failing in the ignition system.
