My car typically idles around 500 rpm and dips down to 400-450 rpm once in a while, especially at lights and becomes a rough idle. If I give it a little gas, or put it in neutral to raise the RPM up tp 600 RPM, all is fine.

Therefore, is there a way to raise the idle about 100 RPM so it idles at 600 RPM instead of 500 RPM?

Thanks

Ben