I"ve never done this personally, but have read it works. Wait till your car warms. Unscrew your idle bolt on the back of the Intake manifold. Unscrew it all the way, but don't pull it out. Then screw it back in. do this 2-3 times and set it where you want the idle. Like I said, I've never done this, but read it works.

I've also heard clean the TB and that'll help some too.