Re: code P1127??
If that is the "only" code you are getting, it is most likely going to be your bank one oxygen sensor. Your not getting a heater circuit code, so I wouldnt suspect wiring, and your not getting a code for the other bank, so I wouldnt suspect a maf problem or a fuel pressure problem.
Without diagnostics, its a guess, but I would replace the bank one oxygen sensor (the side where cylinders 1,2,3 are on a v6, 1,2,3,4 on a v8.
Hope that helps.