when i start the motor in the morning it idles rough till i hold down on the gas on 1991 Chevrolet S10

it has been doing it more often it idles really rough step on gas a little then it will idele better runs really good just does it after it sits awhile or over night

Asked by for the 1991 Chevrolet S10
you may have carbon build up in throttle body or idle air control valve is bad