1995 Ford F350 map sensor

i have a 1995 f350 4x4 7.5 liter 460 motor my truck recently started to surge at idol it even stalled.I took it too a mechanic we checked fuel preasure it was ok he changed the fuel filter spark plugs wires cap and rotor even the o2 sensor still surges and stalls.So he thought maybye the map sensor we changed that the surgeing went away but now when you start it cold it runs real rough black smoke and low idol until it warms up then its fine .We don't know where to look now everything keeps pointing at the map sensor.HELP ME PLEASE.