Small Engines (Lawn Mowers, etc.): Briggs Stratton Model 28V707, murray lawn tractor, briggs stratton

Question
I have a Murray Lawn Tractor with a Model 29V707 B&S engine with a Nikki carburetor. It will only start if I remove the air filter and spray carb cleaner in the throat of the carb. Once it starts it runs ok and will continue to start as long as the engine is warm. It will backfire sometime when I turn it off. And it runs ruff at full speed. Any suggestions as to what the problem is and how to fix it.  

Answer
Make sure the choke is closing properly; sometimes the throttle/choke cable needs to be adjusted.

For the ruff running, clamp off the fuel line or turn the tank valve off.  Remove the carburetor float bowl nut located on the bottom of the carb and drain the fuel.

It's possible, if you're careful to gently remove the float bowl and check for debris in the carb.

How old is the mower?  Has the fuel filter been replaced?  How about the spark plug?

Let me know.
Eric