2011 Scion xB idle speed

So I have a 2011 Scion xB that has had a rough idle for the past 2 years or so. I thought it had to do with the power brake booster because the idle would drop to under 500 RPM when I had my foot on the brake. So I figured there was a leak somewhere in the system. Then it started to have a rough idle whenever I was stopped at a light or even just in park and idling. It was a little irratic. So I decided to replace the cheapest option, the PCV Valve. It ran a lot better but would still get the irratic idle. Just not as bad. So I thought that the computer had been compensating for the air leak. I disconnected the battery for 15 minutes to see if the computer would reset to factory settings. I started it up and now the idle is at like 350-400 RPM in park and drive. When I am driving it is fine. What could possibly have happened to make the idle drop that low? I didn't touch anything else, only the PCV Valve. So I am a little stumped. Is there a way to adjust the idle? Any ideas or suggestions are welcome. Thank you.

 

Sounds like a dirty throttle body, I'd start with cleaning it.

 

Yeah, Sounds like the "learned" idle was cleared when he disconnected the battery.
Throttle Body was my first suspect as well.