you need to trouble shoot it a little further imho to make sure you aren't just throwing parts at it.
You need to get something that can monitor rail pressure to start off and then report back
WOT should be around 24k psi
idle should be around 5k, and crusing should steadily raise rail pressure as you give it throttle, if it does not, or comes up and then drops off then you either have a harness issue or a pump issue. If you have a pump fail you need to be sure there isn't a bunch of metal in the system
pull the fuel filter and look in the bottom of the bowl as well as the filter itself for metal