F 250 4WD Pickup V8-460 7.5L (1984)
Idle Speed/Throttle Actuator - Mechanical: Description and Operation
Vacuum Operated Throttle Modulator (VOTM)
Fig. 33 Vacuum operated throttle modulator (VOTM)
The VOTM, Fig. 33, used on some vehicles acts as a variable carburetor stop. The plunger extends when vacuum is applied.