You can try this.
When you start your car, turn on the AC. That tells the ICV to open to compensate for the load of the compressor. Even if you don't have a belt to the compressor, that is a handy way to know if the computer is actually affecting the ICV at all. If it keeps you from stalling out or your idle raises, you know the ICV and associated wiring is OK.
If there is no change, verify that you ICV is actually working by removing it and watch that the vane inside actually moves when you turn on the ignition. You should feel it vibrating in your hand.
Once you are sure it works, check the resistance of your coolant temp sensor. I don't know what the values should be but if it's out of range the computer won't know what your engine temp is and won't know it needs to compensate.