The first thing I would do is a simple compression check. As long as compression (no lower than 80 psi on each cyl) is good it's nothing major. Had I made this the first step in troubleshooting my stalling it would have saved me 2 weeks of unnecessary troubleshooting and headaches!

If compression is fine chances are your carb just needs a good cleaning. Remove the carb from the engine, disassemble over a clean white cloth and clean each piece well with carb cleaner.

Good luck