Small Engines (Lawn Mowers, etc.): Engine stalling, gas cap, spark plug

Question
I have a 6 year old Craftsman 6.5 HP mower.  I am able to start the engine but it gradually stalls out after about 20 seconds.  I then let it sit for a minute and prime it again and then restart it.  It will then usually start again but sometimes need to repeat the above step.  I have changed the oil, spark plug and air filter but don't have much luck.  Any ideas?  Thanks.

Answer
Hi Brian,

First, check the gas cap to make sure it is venting and not causing a vacuum in the tank.  If that's okay, then the carb most likely has dirt, debris or gummed fuel inside.  You will need to remove the carb, disassemble it, clean all the small internal openings and blow it out with compressed air.   Probe each and every hole with a small wire.   A carb rebuild kit wouldn't hurt either.  

Let me know how you make out.
Michael