2000 Explorer 4.0 pushrod eng A/T lean codes

[Pins Explorer]

I have a 2000 Explorer 4.0 Pushrod A/T getting codes P0171 and P0174 system too lean banks 1 and 2 Have replaced both upstream O2 sensors still code along with P1000 code now What are the possible causes of the system too lean codes

 

[JusTheUsual]

My experiences with those damn lean bank codes is fuel pump, and head gaskets/heads being warped, others will say intake gaskets