Lean bank 1 is not a phantom code. There are specific issues that cause your maf to read weak etc..and it'* a real problem that the FSM gives diagnostics for..then you talk to Foghorn and become an expert on it.
Your problem isn't the O2'*..it'* not the plugs or wires..it'* electrical most likely. Check your connections at the battery..and make sure by pulling off both cables that they are clean. Last 00 owner with this code had a bad post in the battery.
ps..I'm the P0171 king. Search on P0171 with me in the person field. You'll get more info. You'll have it fixed up in no time.