I'M NEW HERE BUT MY WIFE'S EXPLORER IS A 2000 5.0 V8. IT HAD A MISS FIRE ON CYLINDER 7 SO I DID A TUNE UP AND REPLACED THE FUEL INJECTOR, WIRES, COIL PACKS AND PLUGS. FIXED THAT THEN GOT A P0171 AND P0174 LATER ON. I REPLACED VACUUM LINES, PCV VALVE AND EVEN DECIDED TO REPLACE THE ENTIRE EGR SYSTEM. STILL THE SAME CODE. REPLACED MAD AIR FLOW AND IAC, STILL THE SAME. BOUGHT A FUEL PRESSURE GUAGE AND SMOKE MACHINE, 60PSI AT IDLE AND NO LEAKS WITH SMOKE MACHINE. EVEN BOUGHT A DIAGNOSTIC SCAN TOOL AND AFTER SOME OF THE REPLACEMENTS THE FUEL TRIMS LOOKING GOOD NOW. BUT STILL LACK OF POWER AND VERY ROUGH IDLE IN AND OUT OF GEAR? HELP NEEDED! P.S. ALSO REPLACED TIMING SET MONTHS BEFORE THAT AND RAN GOOD TILL NOW. Any help is appreciated

Did the test for vacuum leak and short term ft did not drop hardly at all, stayed around 1-3%

 

WHAT ARE YOUR FUEL TRIMS?
MAYBE THE ATTACHED TSB WILL HELP WITH YOUR DIAGNOSING. Good luck.