Is it a Briggs & Stratton motor? Those are notorious for surging issues on the new Toro's and from what I've read there isn't really a solid solution.Will bump the mower up a notch this time out. Problem is my mower has developed a surge once it gets warm. Local dealer is 2.5 weeks out for service. Newer mower has the plastic carberator on it. I’ve had it off twice. Cleaned it and blew everything else. Spark plug is good. New fuel and cleaned air filter. Just wondering if it developed an air leak that is causing it. Frustrating!