I have a Dixon ZTR with a Briggs & Stratton Intek 15.5 OHV engine. I was mowing one day and the unit went into a high rev, shut it down and i tried to re-start and it popped through the carb and went into a high rev. again. throttle cable is in tact, and governor and all other linkage and springs and things seem to be working properly or at least moving freely. Any Ideas?