Td5 acute "oil in loom" problem?

Have owned Td5s for the past 10 years & thus seen the "oil in loom" problem revealed in various forms.

As of today my '04 Disco Td5 started behaving extremely oddly, subtly clunky at idle (feels as if the vehicle is being given hand pushes from behind), then normal when given throttle, but once boot is off the throttle the engine starts misfiring (not the typical 1 cylinder misfire but something rather massive) and comes to a stop. Engine re-starts as if nothing had happened but said behavior persists.

Nanocom shows 'peak charge long', 'peak charge short' & 'open circuit' faults randomly in all injectors, I have cleared these several times and they keep showing up each time the engine shuts down. Also worth noticing is that "Idle Speed Error" is now between +/- 12, whereas before was well within the +/- 4 range and the engine felt a lot smoother. All other fueling parameters are within specs, also no abnormal smoke, oil level normal, coolant level normal, coolant clean, etc.

Evidence would typically indicate a rather intense oil-in-loom problem but... injector harness is practically new (replaced 2 months ago) and there are absolutely no traces of oil in connectors C0521-C0171 (injector harness to engine harness) and C0158 (red plug to ECU). Checked continuity in all 7 conductors (5 injectors + 2 grounds) from each individual injector connector to the ECU & found no conductivity problems at all. Also verified battery, fuse boxes (relays & fuses), alternator & grounding at various points, all to no avail. Pulled ECU apart just in case... also completely dry.

Though I believe it's fuel delivery related (fuel sender, fuel filter, fuel pressure regulator or maybe CKP sensor), it is the apparent electrical nature of this problem that has me puzzled.

Any thoughts more than welcome.

Regards

Matt

Update:

Replaced fuel filter, no changes, engine still misfiring and shutting down when easing on or releasing throttle.

Found some sort of black soot inside fuel filter & since engine was run on high sulphur diesel until a few months ago (low sulphur diesel previously unavailable in my area...) wonder whether it could be some sort of sulphur residue? (reportedly some of the modern lubricity additives used in low sulphur diesel can act as diluting agents for sulphur leftovers).

There's a small gauze filter inside/behind the fuel pressure regulator (on the incoming fuel line I reckon), has anyone heard of it becoming sufficiently plugged or blocked as to restrict fuel flow into the engine?

Help appreciated!

Regards

Matt

id say crank sensor

Update #2:

Replaced crank sensor, thought I had it since the metal tip was literally buried in oily muck & the car ran smoothly for quite a while, but eventually the misfiring & cutting out returned...

Currently waiting on new fuel pump, will open up FPR and inspect gauze filter. Also coming up with a device to be able to read fuel pressure while driving.