strong gas smell + black around tailpipe- leaking fuel inj?
 

codes and messages:

P0159 lambda sensor aging downstream bank 2

P0174/P0175 additive adaptive mixture correction tra bank 2

P0174/P0175 mixture adaption factor fra bank 2

P0150/P0152 lambda sensor upstream catalyst bank 2

Physical signs - a pretty strong gas odor while idling, running rich. Rough idle. Mpg dropped from 10/15 to 8/12. Also a very black and thick ring of soot around the tailpipe edge.

This can't just be bad O2 sensors?? Mechanic guessing I've got leaking fuel injectors. Could it be anything else?

Bump... Anybody?