wont idle on 2000 Ford Excursion

when i first start it wont idle but when it warms it will only idle at about 500 rpm there is also no engine light lit up to pull a code any suggestions?

Asked by for the 2000 Ford Excursion
I would clean out the idle air control valve, they get dirty and cause this problem, if that doesn't help, clean the throttle body.
good luck