When you opened it up to fix the governor, did you remove either the camshaft or the timing gear on the crank? the internal timing may be off. Seems like on some of the Briggs the crank gear is slid up on a pin in the crank and it will slide out of mesh pretty easily.
I can recall 6-7 years ago working on a 3 hp briggs on a tiller. I worked on it a long time before I realized that the intake valve was open on what should have been the power stroke. Opened it up and the cam was way out of time.
(Best I recall we put in a new cam, then when we got it back together the pto bearing was out. It had been low on oil and that was when it jumped time, plastic cam gear and all.)