Paccar Px8 code PID 157 Spn 1

Hi all, i have a 2010 Peterbilt with the Paccar px8 getting code pid 157, engine will either stall out and fire right back up after a few minutes or derate the motor was intermittent but going on and off more frequently now. Have had a shop go thru the high side and the low side they found nothing, change the pressure sensor didnt make a difference, changed the relief pressure valve made a noticeable difference for a day or two then went back to derating the engine.
Any help appreciated
400,000 miles