Toyota Repair: P0171 C/E code, toyota tacoma 4x4, mass air flow

Question
I have a 99 toyota tacoma 4x4 v-6. I changed pre and post O2 sensors, fuel filter, cleaned throttle body and still get the check engine code P0171. OBD II says it happens at 2600 RPM @ 55 MPH. What else could it be? Please help, thanx

Answer
THE most common cause for this code is that the mass air flow (MAF) sensor is dirty and needs to be cleaned, it's located just behind the air filter in the large intake tube, there are two phillips screws connecting it, remove the sensor and clean the inside with an electronic parts cleaner and a can of compressed air, you can get both at any electronics or computer store, make sure that the platinum wires inside the maf opening are cleaned or just replace it, they are about $100.