Possible causes
- Intake air leaks
- Faulty front heated oxygen sensor
- Ignition misfiring
- Faulty fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Faulty Mass Air Flow (MAF) sensor
- Incorrect Positive Crankcase Ventilation (PCV) hose connection
Read more:
http://engine-codes.com/p0174_2001_ford_windstar.html#ixzz3JXRAoBhY
You could check and clean the MAF sensor - its easy to do just google it
You could inspect the PVC hose and hose connection. Look for cracks or defects in the hose. Easy to fix easy to check
You could check the exhaust and look for leaks in a well ventilated area of course.
you could buy a new gas cap. Its cheap and if the cap is old it wont hurt to replace it.
you could check for misfiring once you get your obdII reader
You could check the air intake, sometimes it gets out of wack and/or the rings connecting the pieces slip
All in all this doesnt look like the end of the world. If you try the easy cheap stuff first and it still doesnt fix it I would pay for a diagnosis. Its that or start throwing expensive parts at the problem and that is rarely the least expensive route.
good luck.