When you say the fuel rail pressure sensor keeps going, what exactly do you mean. Has the dealer replaced any parts for this issue? What code is the computer setting for the check engine light?
Jason_morgan1, the dealer is chasing the wrong problem. The P0191 code just means that the fuel rail pressure sensor has detected that the fuel pressure is going out of range. The pressure could be either too high or too low. P0191 almost never indicates a bad fuel rail pressure sensor.
You are having a fuel pressure problem. Since you say it normally happens at higher RPM's you may have a clogged fuel filter. Chances are though you need a fuel pump. While this is not a common problem, I have seen it several times before.
Hope this helps, if you have any further questions do not hesitate to ask.
Jason_Morgan1, I doubt you have a clogged fuel filter, but there is no way to tell without removing it and checking. A fuel pump going bad, or a fuel injector leaking down can cause a hard to start problem. A fuel injector will not cause a P0191 though.
I am 95% certain you need a fuel pump. Using a scan tool to watch the FRP data, you would most likely see the fuel pressure drop on hard acceleration and higher RPM's.
If I can be of any further assitance just let me know.