I just converted my 1966 bronco to megasquirt. There is an article on this site with a how to with a pro-jection 4d. I was wondering how you got the IAC to work correctly. Do you have a megatune map that you could share. I pretty much have the same setup as below.
http://www.302w.com/Windsor_MegaSquirt_Introduction.aspx
Engine = Heavily modified 289
Throttle body = holley pro-jection 4D 700 CFM
ECU = megasquirt II PCB 3.57
Thanks,
Justin