NPR suction control valve
 

Hi all! New member here looking for some help.
I've got a 2006 GMC W4500 (Isuzu NPR) that has developed the infamous p0087 and p0093 diagnostic codes.
p0087: Fuel Rail/System Pressure Too Low
p0093: Fuel System Leak Detected Large Leak
These codes are only triggered under high load such as when going up a hill at 65mph. The truck goes into limp mode when these codes are triggered and has to be power cycled for it to run right again.
This first started about 2 weeks after I changed the fuel filter and so my first thought was I over/undertightened the filter but I bypassed the filter and the codes were still triggered. Some online say to change the suction control valve so that's what I did. However when I put the new SCV in it ran very rough so I put the old SCV back in and it ran smooth (codes are still thrown under load though). Both the new SCV and the old upon taking it back out for inspection have had their inner seal trashed by the place they mate to. In my picture there should be a seal where my finger is pointing to. Does anyone have experience with these?
Sidenote: I ordered a SCV for a Vauxhall Astra or something because it's the same part but cheaper.
GM part#: 98043686
Isuzu part#: 8-98043-686-0