Couple questions on the code?

2004 5.4 f105 fx4 70K

Started having problems about a year ago under hard acceleration would start to stumble and not pull rrr's past 2500 or so abck out of it and it would run fine get back in it same thing. Had a new filter put in thinkin that was the culprit and I don't ever take alot of trips in this truck so I don't see the problem often. Yesterday three hour road trip and it came back. I am thinking fule pump possibly but not sure any other area to look at? Seems like around town it never happens just longer trips also power does seem alittle down.

Thanks

 

Code P0191 says to start by checking the wiring to the Fuel rail pressure sensor and then check the sensor itself.

 

Yeah , Check the voltage on your Fuel pump relay and check the vacuum on the regulator , but I would suspect the regulator or pump itself .

Pressure check per manual , purchase a Haynes or Chiltons manual for the procedure..

 

Thanks guys will start there.