Neighbor brought a Toro Personal Pace (Briggs 7.0 Quantum) with the blade clutch feature. When it starts with the blade not yet engaged, it surges wildly. But when the bail is pulled thus engaging the blade, it runs great (3200 RPM). Tried several known good & clean (one brand new) carbs & still happens. I even opened the bowl nut jet on one of the carbs with micro drill bits increasing the opening incrementally 3 sizes up from OEM. No success. Am puzzled by this one. Maybe the gov gear inside the engine is the problem. Anyone experienced this?