Strange idle pattern- Blacktop SR20

[teh smithers]

As the title states, my '98 SR has been acting weird. When I start the car up, it idles at about 1800 RPM'S for a few seconds, then drops to about 1100, then bounces back up to 1800. Drop, bounce, drop, bounce, continually. It will do this until I've driven up to the front of my neighborhood, where it'll settle to a steady 1500. First off, what causes this "bouncing" pattern? Second, what makes it idle so damn high? I've fiddled with the adjuster screw on the throttle body, but got no results.

Side note- The motor runs great when in gear, so no problems there. Mods include a GT28RS on the stock tune, full 3in exhaust, FMIC, and SSQV.

[Sileighty_85]

check for Vac leaks and Adj the IACV not the TB

[teh smithers]

Thanks, I'll check that out.

[teh smithers]

Just messed with the IACV until I got a nice, healthy idle of 900 RPM's. No bounce. Woo!