Land Rover LR3 - System Too Lean Check Engine Light (P0171 - P0174)

Only Use DENSO Sensor 197-6020 as a replacement. I diagnose the faults on an LR3 engine ECU and replace the Mass Air Flow Sensor.
Remember that I replaced this sensor after checking the Short Term and Long Term fuel trims. Also made sure that there were no air vacuum leaks in the system. The Short Term and Long term trims were good at idle but all over the place during acceleration.
The Delphi sensors are junk and do not resolve the issue.