Ford Repair: 2006 Ford 500 OBDII code P0191, P0171, P0174, p0171 p0174, 2006 ford 500

Question
Hi Tony!  The check engine light on my Ford 500 has come on for the 2nd time this month.  At the beginnning of August I noticed some hesitation when pulling steep hills and then several weeks later my check engine light came on.  I was sure it was fuel related and guessed that perhaps I had gotten some bad gas....  Went to the local AutoZone and the guy who pulled the codes wouldn't let me see what codes it showed just shoved some STP fuel treatment and some other fuel injector cleaner at me and said that should take care of the problem.  Well, it did work, or at least until yesterday when I was once again coming home along a mountainous highway when it began hesitating again, after pulling the hill and going downhill it seems to be running okay...  Stopped this morning and put some more STP gas treatment in as my son and I were taking a small vacation.  Then while driving over Wolf Creek Pass the check engine light came on again, I didn't notice any hesitation.  When we got to the nearest town with an AutoZone I pulled in and had them pull the OBD codes.  This guy was much nicer and actually printed them out for me.  It is showing code P0191, P0171, and P0174.  I am assuming that the P0191 is actually the cause of the other two codes, the rail pressure sensor malfunction causing the fuel trim to be too lean on Bank #1 & #2.....  But can you explain to me what exactly the P0191 code means??  I know it is sensing that the fuel rail pressure sensor is out of range but I don't know what that means in regular English...  Could this condition be caused by oxygenated fuel?  Or do you think it is more likely something "hardware" related?

Should I be concerned about driving it several hundred more miles before servicing?  I haven't had any problems with it failing to start and it is idling fine...

Thank you for any help you may be able to provide!

Darcy

Answer
Hello Darcy, The code P191 is for a fuel delivery module for the fuel pump. There is a technical service bulletin for this, TSB 06-18-12 for the fuel delivery module. The other codes could be caused from this module possibly failing. Hope this helps to get you in the right direction Thanks Tony