96 F 250 with a 7.5L, EEC V, ( OBD II), P0171 & P0174. I have tried the smoke machine only had smoke out of the EGR valve, replaced it unneccessarily, and the butterfly shaft. Isolated the EVAP & PCV system from the intake system. Fuel pressure seem to be normal under idle and high RPM, changed the regulator any way. Cannot see a way to road test with the fuel pressure gauge hooked up without crimping the tube. Disconnected the MAF sensor and the truck ran worse with a "low circuit" code. Not sure if FMEM was to compensate for this and not kick a code or not. Tried the DPFE sensor as they can cause the strangest codes, NO HELP ! I am at my wits end. Anybody ran across this before ???? Oh by the way those are lean B1 & B2 codes for those who are just browsing. :banghead: