Will clean Maf tomorrow.
I read this article which says that 02 sensor needs to beplaced every 70k and that check engine light might not come on if bad.
http://www.4x4wire.com/toyota/4Runner/tech/O2_Sensor/
Is this all I need? http://www.theautopartsshop.com/Sea...Pat=Year+Auto+Car-USA+Parts+Brand+PartDetails