The DTC’s plus the work you’ve described suggest a fuel delivery problem.
I’m not familiar with the engine specifically, but I can give some generalities that may be useful. That said, I don’t know what the fuel pressure should read. The internets or a manual may be helpful there.
Clogged injectors will give you a weird number. Damaged or obstructed lines ahead of the filter would not be corrected by a pump/filter change and would give weird readings. I believe there is also a fuel regulator in line after the filter that could be obstructed or malfunctioning. The rail itself may be clogged. The injectors may be clogged or may not be working correctly.