FITVs are only on automatics. You have an automcatic GSR?

Also, I'm thinking several things could cause the hunting idle. I'm guessing it only happens when cold?

Here's the thing, if any one component is acting erractically, you're going to get a "pendulum" effect as the motor tried to correct for it. Kind like counter-steering on ice, ya know... too far one way, extreme correction, too far the other way.

Is now an oppurtune time to do a tuneup? How about the boost-bypass assembly on the supercharger (on a JRSC at least). O2 sensor, maybe.

Good luck!
-PHiZ