If your battery has been disconnected for about 15 minutes or so, you may need to perform this procedure in order for the computer to relearn how to idle. Under most circumstances, it will relearn after just driving the car for a while, but if your car continues to experience an abnormal idle, or you just don't want to wait for it to relearn on its own, you can try this procedure.

Restore battery power and turn off air conditioning controls.

Run the engine up to operating temperature and shut off.

Apply the parking brake. Start the vehicle and place it in drive (A/T), or neutral (manual).

Run the engine until the cooling fan has cycled on and off, or for a maximum of 10 minutes.

Turn the ignition key off for at least 5 seconds.

Restart the engine and again shift into drive or neutral. Allow engine to run for at least 5 minutes.

Shut off engine for 10 seconds and restart.

That should do it. With engine stabilized and in closed loop, the IAC motor values should be between nine to 12 counts. If not, the adjustments may be tailored by adjusting the minimum air rate screw. More throttle valve opening equals lower IAC counts. Less throttle opening equals higher IAC counts.