Off hand not sure if you have an internal governor or a flywheel governor as you have stated only the Briggs seris number. The number is either stamped on the sheet metal or on the crankcase. That said I shall continue.
Internal governor. Is it adjusted properly? Is the correct spring used?
Does the arm on the governor attempt to pull the carburetor closed? It should pull the throttle closed. This could be adjustment or internal damage. Does the linkage between the governor arm and carburetor move freely with no hang ups? If not correct the problem. Check for any bent mounting brackets or foreign matter caught in the linkage, governor arm, or carburetor lever. Be sure carburetor lever moves from wide open to idle.
Check the throttle plate inside carburetor is in place and not missing.
Flywheel governor. Most of the same as above. Also remove air shroud and be sure there is no rodent nest blocking the governor arm movement and if the automatic choke is not affecting the governor arm.