Focus mk3 2.0tdci P01169 and P01168

I’m having a major issue with my tdci fuel system. While driving the stability control comes on car goes into limp mode, 10 secs later I get power back and after 2 or 3 times of going to limp it shuts the engine off as well, have to cycle the key in N to start again. At first I got P01169 high fuel pressure in range. Then a day later I got the other code as well P01168 low fuel pressure in range. Iv got both stored. I removed the fuel filter to check it and there’s no visual fuel contamination. I replaced the fuel injector leak off lines as it had a broken clip. I started the vehicle and held the revs up for around 5mins no dramas. I put it in drive and this time I didn’t get 20metres before the car went into limp mode and shut down. Worse than before. Perhaps having opened the fuel system up cud it be air entering the lines to make it worse. I assumed it didn’t need bleeding any air out if it started up fine. I’d appreciate it if anyone’s familiar with this issue and how to diagnose it. I do have the forscan diagnostics. Is there an issue with the pressure control valve on the HP pump or the fuel rail sensor. Hope someone knows wats going on here 

thanks