Now what?? (high idle issue)

[Benfolio]

Drove to work today in the snow (yay!), and noticed when I got off on my exit for work my idle was high, and not dropping. It stayed stuck around 1600RPM. Didn't go away when I tried to play with the throttle at all.

Let it sit all day and it went right back to it after work.

Pulled it inside the nice warm shop and played with it there. Adjusted the throttle cables (no adjustment to be made, really), and suddenly it was fine.

Drove it home (in the snow again, yay!), and went to play in a church parking lot with a twisty fun driveway and it started idling high again. Right at 1600.

Scanned for codes, nothing found, no crap in the intake or anything like that....... possible my TPS sensor is getting stuck/frozen?

Might swap the one off my JDM throttlebody tomorrow.

Any other recommendations?

[impreza_GC8]

Might want to check/clean your idle air control valve as well. There's also sometimes a small set screw on the throttle body itself but you are not supposed to use it to adjust the idle. Make sure its not loose or missing the spring.

[Benfolio]

Idle screw is fine. Swapped IAC valve with a spare and it was fine for a week, now it's back to idling high at MOST times. Sometimes when warmed up it decides to idle normal for a little while, until the gas pedal is pressed again.
It's pissing me off, it's revving to 2500 when cold, the idle hangs (scary on the freeway and annoying when I shift.), it drops to 2000 when I puch the clutch in, but only drops to 1600 when I come to a stop.

I'm going to attempt to swap the TPS sensor today, see if it makes a difference. If that don't work I'll wire up my clutch switch like it should be (just have the neutral switch jumpered right now, has been for months without a problem), because I am still getting a code for the neutral safety switch. Which, by the way, doesn't seem to affect the idle. At least it hasn't since I swapped the trans many many months ago. Maybe I'll play with that too.

[Huffer]

See if you have anything sticking the throttle plate open slightly.

[Benfolio]

It was the TPS. Last time it was in the shop I tapped on it AND the IAC to see if either was stuck and nothing happened. That was the day I replaced the IAC and things were fine for a week.

Today I bring it in, tap on the TPS, and VOILA! RPMs settle down to about 600. Bump the throttle and VROOM! Back to 1600 they go. Tap the TPS again and they back down to 600.

Replaced the TPS from my JDM intake and adjusted it (might be a little too low, actually. saw 500RPM with the headlights and wipers on) and it's back to normal. Actually it's BETTER. RPMs drop down WAY faster between shifts than ever before, unless it's my imagination.