These four codes will show up from dirty MAF sensor wires alone.
P0101- MAF sensor problem
P0137- O2 sensor B1 S2 low voltage
P0157- O2 sensor B2 S2 low voltage
P1171- Lean during hard acceleration

Take a few minutes to gently clean the MAF wires with a q-tip and alcohol or spray 'em with electrical contact cleaner. Do not use carb cleaner.

Mark