Sounds to me like it's time for a good carb cleaning or rebuild. Can you post the engine numbers so we know what you are talking about. We don't know if it's a Briggs, Kohler or a small block Chevy. Sorry missed the bs.
It's necessary to have the model, type, and code this is usually (on an overhead valve engine) on the valve cover, or on the shroud that covers the flywheel.
