check the idle switch clicks when throttle opens and shuts, if not make sure the throttle closes firmly to the stop. if the throttle cable is adjusted too tight it will hold the throttle open a bit.
next look at the wires to the throttle switches to make sure they haven't snapped behind the inlet. the idle switch is on the bottom of the throttle body so is a real arse to get to if it needs adjusting., some kind of angle screwdriver is needed here