P0171 Bank One Lean 2003 Expedition
My 2003 Expedition 4.6 with 95,000 miles is missing and back firing I get all kinds of codes, but consistently P0171 bank one too lean. I have been to private and dealership mechanics and so far piece by piece have replaced.... all of the oxygen sensors, the EGR valve, the 90 degree rubber boots that crack, the pcv valve, intake gasket, coil pack #5 (all the rest tested good), the catalytic converter, fuel filter, air filter, cleaned the mass airflow sensor, had the fuel injectors checked (all good). At 50 driving down the highway it runs the best but still misses. Idling and low speeds it is the worst. None of the parts I've replaced have made a difference. I'm out of money and the mechanics are out of ideas and input would be greatly appreciated.