RyanL

Hello, I have a 2008 Subaru Outback. I bought it about a year ago. Recently it started idling too slow, and even quit on me a few times. Started right up again, but whenever I come to a stop, it gets very slow, low RPMs. 500 RPM or lower. The engine light does not come on, there are no codes, except one time it did have a code: P0172 "System Too Rich Bank 1" I cleared the code (months ago) and it has not returned. Still, the idle problem persists. Is there any idle adjustment? What could be the cause of this? Thanks for your help.