Problem wit idle

My idle stays at 3grand and goes down a lil bit but i dunno y, unless my throttle body fucked up i dunno help me out

could be - sticky throtle cable, vacuum leaks, dirty throttle body not letting the butterflie close all the way, or idle screw is too high

Someone toldme bout the idle screw said that its the screw that in fell and the previous owner just put a diff one in there so wat should i do