Car presented cutting out,occasional not starting. fault codes present:

Intermittent fault. fuel pressure regulator short circuit, open or short circuit to earth.

Intermittent fault. high pressure diesel monitoring, maximum pressure exceeded

Intermittent fault. high pressure diesel regulator blocked

When not starting live data showed
engine speed 160rpm
fuel pressure 31 bar
fuel pressure regulator 4%

After looking through archives I opened up fuel filter to reveal copper coloured fileings. I also removed drv, but couldn't see any particals on tip, cleaned, and refitted. Low pressure pump pressure is 2.5 bar.

After trying car again cutting out returned after 2 mins. while looking at live data fuel pressure would shoot up to over 1000 bar before cutting out.

After doing this for 10 mins the car suddenly started to run right...

Now I know I haven't fixed it, and I dont want the customer to have it back until its right, but I could do with some sugestions of what to try next...

Current live readings are
Engine speed 835
fuel pressure 298bar
pressure regulator 16%

Engine speed 3019
fuel pressure 462bar
pressure regulator 23%

All fault codes have cleared, and car runs well on road test.