These things can really get stopped up. I had one on my Mercedes (btw, same part as the Bosch equipped Volvos) that was varnished up so bad, I couldn't force the valve to move even when I stuck a screwdriver in it and pried. At that point, I was sure it was dead. Since I had nothing to lose, I continued to soak it with carb cleaner, and kept attempting to free it up using the screwdriver. Eventually, the carb cleaner desolved the varnish, and I was able to get it to start moving. Then I ran wires from the battery and began manually activating the valve. After much fiddling with it, it began working flawlessly... and still does.

It sounds like you're at the point I was. If it doesn't work now, you have nothing to lose. Continue soaking it, let it soak overnight, and see if you can "persuade" it free.
Worst case scenario: you're buying a new IAC Valve.

Good luck.

Jeff Pierce
--
'93 945 Turbo ( one kickass family car ! ), '92 Mercedes 190E (my daily driver), '53 Willys-Overland Pickup (my snow-plow truck/conversation piece -- sold to a loving home), '85 Jeep CJ-7 w/ Fisher plow