2003 Taurus losing fuel pressure while driving

Last night my daughter called me and her 2003 Taurus (12V) had died on her while driving. It started back up and ran for a mile or so before it died again.
I went to meet her and it was idling fine. Plugged in a scanner and it had a DTC of P0191 which I believe indicates low fuel rail pressure. Put it in operational data mode and it was showing as 38-40 PSI fuel pressure - as I drove the pressure slowly decreased down to single digits and began to stall. I put it in neutral - coasted to a stop - and while sitting on the side of the road the pressure began to build back up. Start driving and it once again decreased.

Any thoughts on where to start would be greatly appreciated.

Thanks,
Duane

Did you replace the fuel filter yet?

Been out of town just got a chance to work on it - changed the fuel filter, wouldn't it be great if the obvious worked? Unfortunately it didn't. The back flush from the filter looked like day-old coffee but after replacing it the idle pressure is in the low teens instead of upper 30's. Looks like I made matters worse. My best guess now is a bad fuel pump.
Anyone here ever cut a hole in the body to get to the fuel pump? I had an old Honda once that had an access that way and it sure would be easier than dropping the tank.

thanks for any help,

Duane

If there's no access panel under the rear seat, or in the truck.

see http://www.alldata.com, if there's any trade secrets.

It's either a problem with the "fuel injection pressure sensor" or the fuel pump.
The Taurus 2000 and up have an electronic returnless fuel system.
But it really sounds that it's the pump. You can confirm the diagnosis by measuring fuel pressure with a fuel pressure gauge. The scan tool indicates what the sensor reads, not necessary the real one if sensor is bad.
With the gauge, the formula is: Preal = Pgauge + 10 psi at idling. Cause you measures the difference between fuel rail pressure and intake pressure on this system. At off, don't add.
If you have to change the pump, you have no choice but to drop and open the tank. No cut.

I replaced the fuel pump in my '02 last February. I approached it with much trepidation, never did an in tank replacement before. Bought a Carter from Napa, was under $200. Enough instructions came in the box to do the job. Just make sure the car doesn't fall on you because the rear has to be totally suspended. Took me abt 5 hours.