I trying to help a freind, his 96 V8 Explorer is running like crap and getting terible gas mileage, he had it scanned at AutoZone and the po171 and 174 codes came up. Looking for a place to start. Thanks

 

When was the last Tune-up performed??

PO171 system too lean (bank one) and
PO174 system too lean (bank two)

Clean your MAF sensor with a cleaner that will not leave a residue, change the air filter.

Reset CEL.

If this does not cure the problem look for unmetered air in the intake manifold, Vacuum leaks.