keep getting error code PO171

1996 FORD CONTOUR
160,000 MILES
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WAYNEWEATHERMAN
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i have replaced Fuel Filter,Air Filter,MAF Sensor,New PLUGS,THERMOSTAT,WITH OLD MAF SENSOR HESITATES ON ACCLERATION,POOR GAS MILEAGE MAYBE 250 MILE PPER TANK,WITH NEW MAF SENSOR MISSES AT IDLE GETS A LITTLE BETTER HAS IT WARMS UP,HAD INJECTORS CLEANED,I USE TO GET 400 MILES PER TANK,DON,T KNOW WHAT ELSE TO TRY ? MAYBE FUEL PUMP,EGR VALVE,PVC NO LEAKS,INTAKE MANIFOLD NO VACCUUM LEAKS, HELP PLEASE
Sep 22, 2012 at 6:13 AM
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KHLOW2008
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Which engine do you have?
Sep 22, 2012 at 8:26 AM
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WAYNEWEATHERMAN
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also has new o2 sensors,It has a 2.0 16 valve Ztech motor
Sep 22, 2012 at 8:36 AM
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KHLOW2008
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  • 41,814 POSTS
These are what can cause a P0171


HO2S and sensor connection.
Vacuum systems.
Fuel injector and/or fuel injector circuitry.
Powertrain Control Module (PCM).
Electrical circuits (HO2S, HO2S GND, INJ 1-8, VPWR and SIG RTN).

To prevent replacement of good components, be aware the following non-EEC areas may be cause of driveability concerns:

Ignition system.
Faulty evaporative emission system.
EGR and/or PCV system.
Air intake system.
Engine oil contamination.
Fuel system.
Exhaust system leaks or restriction.
Engine cooling system.

A scan tool would help for diagnostics.
Sep 22, 2012 at 8:59 AM