Use gum cutter, the right kind of course, and clean the valve part, not the motor. I use to spray a lot on the valve, put something over the opening and shake, maybe 2 or 3 times. Put it back on the car and try it. Or you could always buy a new one to go with all the other new parts you got.
UPDATE: John came over this past Sunday and we worked on the IAC valve and made idle adjustments, set the timing, and check the internals of the distributor. With John's idle adjustments to the primary and secondary idle screws on the throttle body eliminated the fluctuating idle or idle hunting. It's steady now. However, the car still idles and runs rough with the IAC valve connected. When it is disconnected it runs great. Either way, IAC valve connected for disconnected, the check engine light remains on.
On my last Mustang I had to replace the IAC valve several times. The original valve lasted 100K but after that they went bad every 50K miles. Cleaning it out with carb cleaner did not work. The other thing that causes idle problems on my 90 GT was O2 sensors going bad.