Small Engines (Lawn Mowers, etc.): Briggs and Stratton, briggs and stratton, dirty air

Question
I have a trail mower with a Briggs and Stratton.  The mower spits and sputters and it gets worse when I go over thicker grass.  It does mow but appears to strain.  If I do not stop and let the mower build up speed again, it will cut off.  Last year it ran fine.
Please help.  
Model= 28B702
Type=  113-EZ
Code=  0212052D

Answer
Unfortunately many things can cause your condition. Dirty air filter, old spark plugs, a carburetor in need of rebuilding, weak fuel pump, a weak magneto, or one not properly set, a worn out engine, fuel filter, the list goes on, when was the last time this engine was serviced by a professional?.....Sounds to me to be a fuel issue though, either to much fuel or not enough, your more than likely going to be looking at a carb rebuild, or fuel pump if the other things mentioned are in good shape. Keep in mind 99.9% of most small engine problems are directly related to the fuel system.....Tom