Small Engines (Lawn Mowers, etc.): gas lawn mower, briggs and stratton, lawn mower

Question
My  Murray lawn mower that I have for two plus years was working fine until yesterday.  While I was cutting the grass, it started to sound like it was about to stall out.  It sounded like it needed gas.  So I added more gas added 2 ounces of oil. It started fine but sounds like its about to stall.  But it doesn't. Please help.  Thanks This is a Briggs and Stratton 3.5 engine

Answer
If you have been using it, I suspect either the air filter is dirty, the spark plug is dirty or there is debris inside the carb.  Start by cleaning or replacing the air filter and check the plug (replace if oil fouled).  If this doesn't correct things, check for a mixture adjustment on the carb...it should be set at 1 1/2 turns out from lightly seated.  If you get no response from the mixture screw, the carb is dirty and will need to be cleaned thoroughly.  Hope this helps.