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Not sure what the actual term is but the engine surges at lower rpms. It starts great every time and runs well at high throttle but not at lower speeds. Also the throttle slides down on it's own. (see video in link) Any diagnoses based on the video? Air filter is clean. Spark plugs are good. New oil and filter. New gas filter. I ran some seafoam through with the gas (not sure if that is a myth or not).