So a little while ago I was having idling issues on my legacy and it would stall out on occasion. However it I found out there was a rubber plug missing on the casing for one of the air filters, I sealed the hole (why they put the hole there in the first place I don't know) and it stop stalling and now works fine, however it still bothers me that it idles really low, only about 200 rpm, and somewhat rough too when the engine warms up. It doesn't cause any issues however its clearly to low, so im thinking about cleaning the idle air controller (there's about 172k miles on the car) and sooner or later getting new plugs and tips for i, will this up the idle and make it smoother? any other suggestions?

Service the IAC if it could be carboned or stuck closed. Also, replace the engine temp sensor as if it is failed, the IAC may think the car is warm on a cold start.

 

Oh, hey, i just saw you are in Milwaukee. Count on me if oyu need someone to look at your car for an opinion. do you know if anyone else has messed around with the throttle body?

 

It is possible you could have a MAF problem depending on the symptoms. If what i am thinking your car has an ej25d DOHC, you can trim the IAC by loosening the screws and clocking it one way or the other to manipulate the idle. If the screws are rusty, use a good #2 phillips bit and driver or use a flat jaw vice grip if they strip out.