Chevrolet: idle adjustment, chevy tahoe, throttle valve

Question
How do you adjust the idle on a 1999 chevy tahoe?

Answer
Hello Joe,

On the top of the engine, there is a large metal part called an intake manifold. Attached to it is a valve called the throttle. It is opened and closed by the gas pedal via a cable wrapped around a small spool-like device, which actuates the throttle valve when you push the gas pedal. When the engine is idling, the throttle is held slightly open by a screw, either on the spool or on the valve. By adjusting this screw in and out, you can change the speed that your engine idles. If you adjust the screw so the valve is more closed, the engine will idle slower; the opposite is true.