I've worked on some Briggs, and some Tecumseh. Not sure which yours has.
My suggestion. Remove the air cleaner to get more room to see. On top of
the carb, there is a somewhat triangular metal plate, that hooks to the
throttle. And typically has a stif metal rod that goes to the governor, and
to the spring that pulls the throttle open. This throttle plate should have
a small slotted screw, which sets the lowest speed for the throttle. Idle
speed, they call it. Give that small screw 180 degree turn clockwise, and
see if that helps.
While you have the machine this far apart, consider removing the carb, and
replacing the gasket between the carb and the engine. Two nuts, and then the
carb should come off easy enough. Those gaskets are known to go bad. If the
gasket comes out easy, give it a very light coat of Permatex #2b non
hardening gasket sealer, and put it back in. Sometimes air gets in past the
Christopher A. Young;
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