1996 F-150, 4x4, auto, 5.O, no air pump. Installed long tube headers, dual exhaust, no crossover pipe. Runs good until lean code pops up. Both banks lean, evap system purge valve malfunction. I have replaced both front O2 sensors and installed extensions. WTF need help trying to figure this out.

 

Welcome to the F-150 forum! Glad to have you join us.

Hope you get that issue figured out.