Here is a vid about cleaning and checking the IAC valve.
YouTube
Since its older then a 99 you will need to have it tail pipe tested and obd2 check done to pass CA smog. Fix the high idle issue and you should be set. Warm it up before you have it tested.
Back in the day (4 or so years ago) I had my smog guy fail my miata. He said my emissions were to high. Ok I replaced my cat (18 year old cat) retested and failed again. I was pissed at this point so I came back (changed nothing) and retested. Well it failed, but this time I watched what he was doing. Over revving and over loading (lugging) the engine at the low and high speed tests, passed at idle. So I told him to do the test properly and it passed flying colors. Never went back to that place again.
Anyways hope the vid helps you out.