Consuming too much gasoline

Hi, I have a Ford Explorer 2006 Eddie Bauer Edition which currently consumes between 20 and 21 L/100Km, which is too much, i checked with forscan and it says the combustion is too lean or something like that, i checked and it says that i need to clean the MFA, done, check if there is a broken pipe, done, there was nothing, i dont really know what else to do.

===PCM DTC P0171-FF===

Code: P0171 - System Too Lean Bank 1

Module: Powertrain Control Module

Diagnostic Trouble Code details

System Too Lean Bank 1

The PCM monitors the adaptive fuel table to ensure fuel control system components do not vary from their nominal values. The fuel control strategy within the PCM uses the adaptive fuel table to compensate for normal wear or aging of fuel control system components. The code is set when the PCM can no longer compensate for additional changes in the fuel system.