Small Engines (Lawn Mowers, etc.): craftsman 6.5 mower, briggs and stratton, acre of land

Question
I have a Craftsman 6.5 with a briggs and stratton.  I can't seem to keep the thing running.  I am pretty hard on it I am clearing an acre of land and its pretty rough and dusty.  I've cleared out the air filter and so I don't think it's having a tough time getting air, and I pulled the gas line and it seemed to flow easily.  I've decided that the problem starts at the carb.  the carb seems ok but I'm no expert. The engine will run for about 15 seconds and it sure seems that itcan't get enough fuel but I can't figure out why.  Can you help?

Answer
 Hello Kurt:

 1-Remove and Check the Exhaust Port and Muffler for Blockage. 2- The Carburator May have Pulled Trash/Water Into it. Also the Gas Forms a Varnish and Restricts the Gas Flow Through the Ports and Passages Inside the Carburator. Soak the Carburator Overnight in Cleaning Solution and Blow All the Ports and Passages Out with Compressed Air. Hope this Helps. Let me know what Happens, Please. Thanks.

 Good Luck

 Respectfully

 John