Toyota Repair: Check Engine Light, mass air flow sensor, mass air flow

Question
I own a 1999 Toyota 4 Runner, V-6, Automatic Trans, Calf. Emissions, and 784500 miles.
About 8 months ago, my check engine light came on with a P1135 code. I replaced the air/fuel sensor and that problem was fixed.
Just this last month my check engine light came on with a P0171 code, then the check engine light went off by itself then came back on about 2 weeks later with the same P0171 code
I then cleaned the Mass Air Flow sensor with electrical cleaner and replaced the Air Filter as you suggested.
I cleared the previous codes but the check engine light came back on the next day with the same P1135 code.
Are there any other places I should check?


Answer
The PO1135 trouble code refers to the A/F ratio sensor on bank1,sensor1, this sensor is located on the right bank of the engine(passesnger side) is this the one that was replaced?
If the driver's side sensor was replaced it was the wrong one and the sensor on the passenger side needs to be replaced now.