Not enough information- - - - -is the part operated by vacuum or electricity? Some early carbs had a vacuum-operated "dashpot" that would ease the throttle plates closed when the pedal was lifted quickly after a snap acceleration to prevent stalling. Later on, an electric throttle stop was installed to drop the throttle plates fully closed on engine shutdown to prevent dieseling from the high idle speeds that early attempts at emission control required. There was also an electric throttle stop on some carbs that kicked the idle speed up when the air conditioner compressor clutch cycled on.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!