2004 master dci cutting out P0191

Hi folks I'm hoping someone on here can share some knowledge :-)

My recently acquired 2004 master 2.5 dci is cutting out with the fault codes P0191 fuel pressure sensor signal improbable.

It sometimes drives for 30 miles with no fault, then other times it lasts 3 miles and stumbles and dies, but always swiftly restarts.

There's no visual leaks around the injectors and I have already replaced the fuel rail pressure sensor at a cost of £120 to no avail.

Putting it on live data earlier the fuel rail pressure was 50k then 60k then dropped rapidly to 17k then bounced back to 60k and shut down.

Any ideas before I lose even more of my marbles?

Thanks :-)

2004 master dci cutting out P0191