Re: oxygen sensor
Just because its lean doesn't mean that its bad, fwiw.
I have never changed the 02's on my mustang, but I have on my camaro and its not that big of a deal.
Find where they plug in.
Unplug them from the harness.
Plug new ones in and screw them back in.
EDIT: Just read the part about bank2. It should be on the passenger side.