How do you adjustment the idle on a 2005 Expedition?

If you have a carburetor, there is a crew on the driver side behind the throttle cable it usually has a spring on it if you turn it to the right it idles up left it idles down

If its a fuel injected motor idle is handled by the computer. There usually is a "base idle speed" around 800-1000 RPM. This normally doesn't need to be adjusted.

Have a look for carbon build up on the butterfly as well, this will influence idle too.