Ford bronco II with strange idle issues?

Friend of mine bought a 1984 bronco II with a 2.8 V6 2 barrel carburetor. Thing is when its cold it will idle at 1500 rpm's and when it warms up it idle's higher and then turns it self off. I checked the timing which is at 12 degrees. Any suggestions? Its a rebuilt motor with a manual transmission. The idle screw on the carb is turned all the way in where its not touching the throttle cable.