Small Engines (Lawn Mowers, etc.): Not running right, spark plug, sponge

Question
My lawn mower will start but does not run correctly.  It also acts like it wants to cut off but doesn't.  I have cleaned the sponge like filter (can't remember what you call it), I have drained the gas and put new in, and I have also changed the spark plug.  Before I did all this it would not even start.  Now it will start but I still can not cut the grass because it does not run steadily.  The mower is approximately 4 years old.  It is a Murray, throttle free 2 n 1, push mower.  If you could please help me with this I would appreciate it.  I don't have a lot money so I can't afford to take it somewhere to be fixed.

Answer
Hi Nora,

The carb may be gummed up or have dirt inside and may need to be disassembled, cleaned and maybe rebuilt.  If it has adjustable mixture screws you may be able to try adjusting them to give better power and smooth running.

Let me know what you find.
Michael