Small Engines (Lawn Mowers, etc.): mower wont keep running, craftsman riding lawn mower, riding lawn mower

Question
My craftsman riding lawn mower will start, using the choke when cold, but once it starts and I raise the throttle and push in the choke, it dies.
It was running fine when my niece was mowing, then she came in the house to take a break and when she went back to mow again this is what it was doing.  I have replaced the fuel filter, made sure the holes in gas cap were not clogged and I'm not sure what else to do.  I really don't want to call a repair man.  Help! I performed a tune up last summer. Can you give me suggestions on what exactly to check or replace.
Thanks

Answer
Hi Regina,

Check the air filter first but I think the problem is a lack of fuel flow.  The carb most likely has dirt, debris, gummed fuel or water 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