42" Craftsman stalls after 3 min run?

After mowing about half my one acre lot my Craftsman 42" model 917.271131 suddenly stopped running, as if I had shut off the ignition. I changed the spark plug, air filter, oil and oil filter and fuel filter just to be safe, but this thing will start right up after sitting for about 3 minutes; run for three minutes and then stall. I let it sit for a few minutes and the same thing happens-starts up, runs for 2 -3 min. and dies. I'm thinking electrical but what?? I'm from the era of points and condenser, so I'm pretty well lost at trouble shooting this thing! Anybody have any ideas? TIA Art Lee