1. Check for vacume hose leaks.
2. Replace the Fast Idle Valve
3. Replace the EACV
4. Pray it isn't your Throttle Position Sensor (it was that and the EACV on my SiR). If so, don't try and adjust it - get a new Throttle body with a factory sealed TPS.
5a. Drive it off a cliff and claim insurance as it's the only way you might get your money back on all of the above

or

5b. Take it to a mechanic where they can check all of the above