How do you keep idle constant on 1987 VW cabriolet?

To keep the idle constant on a 1987 VW Cabriolet, first ensure that the throttle body and idle air control valve are clean and functioning properly. Adjust the idle speed using the idle adjustment screw on the throttle body, typically found near the linkage. Additionally, check for any vacuum leaks in hoses and intake manifolds, as they can affect idle stability. Finally, ensure that the ignition system and fuel delivery are in good condition, as these components also impact idle performance.