Revhead95

I recently had a terrible missfire problem. tore down the top end and replaced gaskets, plugs, wires, and deleted the EGR system. Now the missfire is gone completely, but at cold start it Idles at about 1900-2000rpm and when its warm the idle drops down to about 500-600 and surges up and down constantly. If i hit the gas its fine with no hesitation and idles down slow until it hits idle speed then surges again from 5-600RPM. I searched on here and its mixed finds. im stuck figureing out if it is Vacuum leak, IACV, MAF, or TPS bad?