Can someone inform me as to what this does/is for?
I did a once over yesterday looking around, saw this and plugged it in before my drive. Car ran like cr@p, like it was stuttering, RPMs falling at idle then would jump back up. Pulled over after a little and unplugged it and like new again

 

it's the idle control valve. As the name suggests it regulates the idle speed depending on other system parameters like temp, engine load etc.
Yours might be damaged and/or fouled. You can test it with an ohm-meter or clean with carbs cleaner.

I wonder if your car stays on if you switch the AC on?

 

You should download a copy of the Factory Service Manual from the FAQ stickys at the top of this page or the 3rd Gen. Tech section. It'll have more information about testing the IAC. Then think about properly removing the throttle-body coolant and AWS which apparently the PO didn't do.

 

Thanks for the reply!
And yes the car stays on with the AC (all though it does not blow cold, thats a prob for another day )

 

Thanks for the info! I do have the FSM just looking for a little more info on it I guess.

Will clean and what not as stated above, but since it runs fine without it am I ok?

 

Yes, you're ok. Some people even delete it and use block-off plates instead. The fact that it malfunctioned for you might also be related to you PowerFC settings (I've no experience with PFC though). Anyways I wouldn't worry much as long as the car idles fine.