This is what I saved a while back... I think I found this on the Corral....
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The "idle screw" that everyone is referring to is actually a throttle stop. It was never intended to be used to adjust the idle because the computer is designed to control the idle to a preset level programmed into the ecu - 672 rpm. It does this by monitoring rpm and telling the IAB solenoid to let more or less air bypass the throttle plate to stabilize the speed. While some folks have luck setting the idle speed higher, just as many only create a machine that constantly surges and hunts for a constant idle speed as the computer "fights" with your attempts to increase the idle speed by turning the throttle stop screw. You should also reset your tps level down to .95V or lower - having it up around 1.0V (.99V) can also cause the idle speed to do funky things. If the idle problem appeared NOT as a result of other changes you made I'd try this:
1) remove throttle body and iab solenoid and clean them thoroughly; reinstall
2) Set the throttle stop back to its proper location - back it completely off (unscrew it); place a .003 feeler gauge between the screw tip and the throttle arm; tighten it til it just touches the feeler gauge; then remove the feeler blade and tighten it 1/4 turn more.
3) Set your tps to .95V with the ignition on/engine off but warm
4) Disconnect the battery with the headlights turned on - leave it disconnected with the headlights on for a minute or 2.
5) Reconnect the battery and crank it up. During the next few hours (cummulatively) of driving the computer should 'relearn' and begin controlling the idle with more stability.
Good luck!! Chasing down funky idle issues is one of the toughest things the efi crowd deals with.
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Worked for my car for the most part. I surge a bit when the car is warming up, but its fan wash from the clutch fan air hitting my cone I think... and after it warms up to temp, still its pretty steady on my car