atrdriver

My 2011 Edge Limited AWD started to idle rough the other day, and the check engine light came on throwing codes P0018 Bank 2 Sensor A and P0021 Bank 2. I normally attempt to do my own maintenance, at least when I can. What are the possible causes of this? Is there anything that I can do to troubleshoot without throwing parts at it? It also seems to have lost some power, but I didn't really try to run it hard after the symptoms started. In fact since then I haven't had it over about 35mph. And haven't driven it since the day it happened. I would rather not have to go to the dealer, but obviously will if I have to. I doubt that it makes a difference but about a month ago I replaced the oil pressure switch. Thanks :)

It has about 145K on it. That seems pretty early for a timing chain, but then again I have seen some weird stuff on this car. I am pretty mechanical, and worked as a mechanic for several years back in the 80s. But these cars are totally different animals compared to back then.