Small Engines (Lawn Mowers, etc.): Kohler CV14T, fuel filter, magneto

Question
I have this old jacobsen commercial walk behind. Heres the problem. Everytime I get this out I get it started with a little starting fluid. The thing fires up and runs like theres no tomorrow. If I cut it off and try to start it again I cant get it to start with just using gas or using the fluid. It will not even fire once in 50 pulls. Today I changed the oil, new plug and fuel filter thinking this would solve the problem. Still the same thing...would not start. Cleaned the magneto off since it was small amount of rust.  Should I take the carb off and rebuild or just clean everything up.  

Answer
I would start by cleaning everything.  This will help with cooling and help you see if any parts are wore.

Have you tried installing a new plug when you try to re-start it?  Have you checked the engine compression?  How old do you think the engine is?
Let me know.
Eric