I know this isn't a whole lot of help, but on my car, with good voltage at all connectors, properly functioning, stock, etc., yada yada yada, my Bird will idle around 1500 while coasting if I'm in neutral or in gear/clutch in when I first start it up and drive it around. It'll stay at that 1500 for a couple of seconds after I come to a complete stop. Once the temp gets to around 160+, it'll idle at its usual 1k rpm when coasting, stopped, etc. Dunno why it does so, but I think that being about 500 rpm higher until it warms up is normal, unless I have a dirty/broken/needs to be reset IAC. Did you try cleaning your IAC?