See if you can get your hands on a known-good IACV and switch it into your car temporarily. If it idles fine then you know you need to replace your IACV. Otherwise you can buy a new one and if it doesn't fix the problem then you could try to sell it or something. But I would try to find a known-good one first.

Also you may have something as simple as the vacuum hoses running to and from the IACV being messed up going on.