Have a 1995-2005 Dodge Neon with a set of huge lobe cams? If so, and you need to adjust your cars idle after installing the cams, you will NOT want to adjust the idle by adjusting the throttle stop screw.
If you adjust the throttle stop screw, your car will have idle, and run really erratically due to the pcm seeing 10-15% throttle, but yet super low levels of vaccum.
So, we have designed this piece that will allow you to manually adjust the vacuum that flows through what used to be the electronic Idle Air Control motor. When you unplug your IAC wiring, you will NOT see a check engine light!
More info here: