Okay I have a crazy problem. I have a 1997 F150 4.6L W engine code. I have decent in depth knowledge of Ford trucks but this one I am stumped. I have too trouble codes P0171 and P0174 (too lean bank 1 and 2). I have search for a vaccum leak everywhere and came up empty handed. I have check fuel pressure and it sits at 30 psi while running. I have checked the ohms resistance on my injectors and every one reads at 15.3 which is normal. To top it off it's a brand new engine and I don't need detonation to ruin my pistons and thus eliminating any warrenty. I have also replaced dpfe sensor, idle air control, mass air flow, every vaccum line, and knock sensor all to come up short. I'm absolutely stumped. It has new fuel filter and I know 30 psi to the rail is on the lower side of normal but it's still in that gap. I can't figure this out and need help. Do you think it could be my ECM? Anyone with similar problem and possible cause of this or found what fixed their problem please help

 

Did some google searching and came up with a possible faulty mass air flow sensor. I actually had this code come up on my truck and after a new battery it reset and the check engine light never returned. Lucky I guess.