Lawn mower runs up and down not steady?

Question

This mower runs but it is never running steady after this winter. It was bought spring of 2007 new. Do you know how to fix it to run more stable. When it is about to run out of gas it runs very well for a minute until the gas is gone. I am thinking that a fuel additive would help because it seems like the gas line may be clogged and gas is not getting to the engine.

http://www.uploadhouse.com/viewfile.php?id=2305004

Is this the air filter? It is a yellow foam filter. i have cleaned this but didnt do much.

http://www.uploadhouse.com/viewfile.php?id=2305003

What is the silver circle being pointed to?

http://www.uploadhouse.com/viewfile.php?id=2305001

Answer 1

mine does that too. i was told it was the carb., but i have another lawnmower i use.

Answer 2

most common cause of eratic RPM is leaky carb or intake manifold gasket.  Another cause:  old or watery fuel.

yes that's the air filter.

silver circle is the muffler.

if you want to use a fuel additive, try Seafoam -- can't hurt.