Where is the IAC valve located?

It is mounted on the side of the throttle body. If you replace it or clean it, you will need to do an idle reset. For that you need either a scan tool or a short wire and a tachometer. The scan tool is simple, you select the idle speed then lock the parking brake on. Next you run it up to 2000 rpm with-it in-service mode for ten seconds. Exit service mode and let it drop to idle. Shut the engine off and restart to verify it idles correctly. If you don't have a scan tool you go to the ALDL connector under the dash. Look at the orientation of the connector and verify the location of pins A and B. Those are the two you will jumper to enter service mode. You then follow the same steps. Jumper in, run up to 2000 rpm for ten seconds. Let idle. Now remove the jumper. Test that it starts and idles correctly.
Do not push or pull on the pintle on the valve.