Well, from what i'm seeing with googling the code, this is your problem
System Too Lean (Bank 1)
This means that an oxygen sensor in bank 1 detected a lean condition (too much oxygen in the exhaust).
These may be your causes
A code P0171 may mean that one or more of the following has happened:
* The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
* There could be a vacuum leak downstream of the MAF sensor.
And then some possible solutions
* In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
* Inspect all vacuum and PCV hoses, replace if necessary
* Check for a dirty fuel filter and proper fuel pressure
Thanks to google for all the info.
2000 2.5L Ford Banger
What I've Done: Pioneer Head Unit, Nexen 31" Tires, Projector Headlights, Manual To Power Locks, Jet Black Paint Job, American Racing Baja Rims, Billet Grille, Herculiner, Rail Caps, Tinted Windows, Explorer Radio Bezel, Wired Bezel For Projectors, Kicker Sub/ Visonik Amp, Black Carpeting, Kicker 6x9 Speakers, High-Flow Air Intake, New Horn, Black Interior. Center Console, many more still in process.