Post the model and type numbers of the Briggs so we can see how the governor is setup on your engine.
Either it has air vane or internal governor. Either way there is no spring to return to idle. The air vane version uses the air pressure against the spring to close the throttle butterfly vane and the internal does a similar way but it uses spinning weights acting against the spring. But I doubt it is using both methods at the same time. The air vane may just be a auto choke control.
If an internal governor setup then either the static governor adjustment is off or the governor has failed. On the air vane version the air vane could be sticking or not receiving air flow.
