I suggest it's time to remove the IACV, inspect carefully and decide if it's repairable.

If not repairable, replace w/ new or used. You may have to buy an entire throttle body to get an IACV, but plenty of throttle bodies are available for <$50 from car-part.com.

IACV as a part is pricey; > $200 from Rockauto, so OEM is probably even more.

good luck

Just ordered a used IACV off eBay for $33.00. Will post back results. Thanks to all.

Gary

I received and installed the used IACV today, reset the ECU, and everything works great. No surging idle after warmup. The idle settles down nicely around 700-750 and stays there. When I took out the old IACV and compared it to the new one they were identical except for one thing. The "plunger" on the new IACV was seated tightly. The plunger on the old IACV was not, but the only way to see this was to shine a small light through the screen while looking at the end of the "plunger" through the hole without the screen. Then I could see just a little light shining through.

I don't know if this is related or not, but the clock located above my radio has not worked for about a year (did not light up). I just figured it was broke. But for some reason it is working now after replacing the IACV and resetting the ECU. Could a bad IACV have kept my clock from working?

Thanks again for walking me through this. Can't believe this car is working this good at 334K.

Clock is almost certainly a coincidence. It will probably quit again soon. I've repaired a Subaru clock that had loose solder connections on the surface mount resistors. If you're handy w/ a soldering iron, it may be worth removing the clock and examining the circuit board closely w/ magnifying glass, looking for cracked or separated solder connections of the surface mount resistors. Subaru had about 3 resistors about 6mm x 2mm.

good luck