2000 Mercury Sable V6 Front Wheel Drive Automatic 65000 miles
The car has been extremely well-maintained and never experienced any mechanical problems until now. The check engine light came on; codes ran at AutoZone indicated #P0171 and P0174--lean fuel. Mechanic found vacuum leak, crack in elbow of vacuum harness and replaced, and cleaned intake/throttle body. Light returned after driving two days, and car sputtered (then car drove sluggish/felt " clogged", not shifting-accelerating properly, idled longer/higher in a.M, extreme exhaust odor). Mechanic ran codes--emission control faults/ECM stored three fuel metering codes; replaced upstream and downstream oxygen sensors (non OEM). Light returned while driving first day with same sluggishness/odor. Mechanic replaced spark plugs with Motorcraft plugs (had Bosch Platinum installed in April '07). Light returned after driving a day. Mechanic replaced all oxygen sensors with Motorcraft sensors. Light returned. Mechanic currently replacing mass air flow sensor (also checked catalytic converter and showed okay). What do you feel the problem is? Thanks. Tim
P.S. The fail sequence is always the same…first the light comes on, then exhaust has odor, then performance problems begin.