Yeah i've had quite a bit of time trying to get the idle issues worked out, but so far i've only come up with this as a temorary solution...

I removed the stock IAC, and then drilled/tapped the pintle hole in the throttle body for a bolt. I used a larger washer on the bolt that perfectly fits inside this larger diameter part on the TB where the body of the stock IAC fits against..its kinda hard to explain it..I then sealed that with RTV. So now, the IAC bypass air passage is blocked off, and idle is now controlled by the throttle plate. There is a thin metal cap covering the throttle stop screw, and I just turned that out to raise the idle to the right RPM when fully warm. When the motor is cold, you have to put your foot on the gas pedal just a little to fire it up, and keep it on the gas for like maybe a minute or so. After that, it idles a bit low until its fully warm, but the idle is very stable, almost better than stock. I use around 13 degrees of timing at idle, and run it a bit rich into the low 13's, as this helps to keep it idling when cold without using the gas pedal.

There are mechanical/electrical air bypass valves on some Volvo cars, that let extra air into the engine when cold, and as it warms, closes it off slowly. This would be the easiest form of an IAC, which needs no connection to the MS.