I have a riding mower with a Briggs 20HP Intek engine. A couple of years ago it started sputtering when put under a moderate load. The problem is worse when going up a hill or in a tight turn. Once the sputtering starts it usually won't stop without depressing the clutch to stop the mower or briefly placing the throttle in the choke position. The sputtering is everpresent but does have periods where it is better (almost gone) though, sometimes it is almost unbearable. I have tried cleaning the air filter, changing the fuel filter and adjusting the carb. Nothing seemed to make a difference.

Measuring Tools & Sensors - Briggs & Stratton - Briggs Stratton Intek V - Twin Vertical Ohv Engine with...