Throttle Opener

Ensure transmission is in Park (A/T) or Neutral (M/T) and parking brake is applied. Warm engine to normal operating temperature. Ensure all accessories are off.
While engine is idling, disconnect and plug vacuum hose at throttle opener. See Fig 1 . Engine speed should increase to 1700-1800 RPM. If engine speed is incorrect, adjust throttle opener adjusting screw until engine speed is correct. Reconnect vacuum hose and ensure engine speed returns to idle.

Fig 1: Locating Throttle Opener & Stop Screws (Tracker)

Courtesy of GENERAL MOTORS CORP.