Opel Vivaro van cuts out when body is jolted, e.g. door closed, WTF???

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Our Opel Vivaro -03 1.9DTI (same as Renault Trafic and Nissan Primastar from that era) van has a weird problem.

It cuts out when driving slowly e.g. over a bump, or even when parked and idling, if some relatively small shock comes to the car's body, e.g. closing a door. You can hear this happening in the video.

After it has cut out it's hard to start like there is no fuel in the system. But after a while it starts and then runs perfectly smoothly, both idling and revving, until BODY is jolted/slammed. Even slamming van back door shut can stall the engine!!

No matter how heavily I do it, whacking the top of the engine, the bottom of the diesel tank, or any of the main relay/fuse boxes DOES NOT cause it to stall.

Doesn't seem to cut out either when wiggling any of the wiring in the engine bay or below dash, or when tapping any of the engine electrical components e.g. MAF sensor, crankshaft position sensor, ECU box...

Thus, it seems like it's either fuel lines related somehow (can it be???) or if electrical, something that's directly attached to the chassis i.e. grounding/earths. Or what do you think?

I already cleaned and retightened battery terminals and engine main grounding lugs with no change. Wiggling or tapping them or their wires when van is running doesn't cause the stall either...

Already went to local Opel dealer car repair shop 3 (THREE!!) times and they just replaced crankshaft position sensor or some of its wiring each time, but as soon as on the way home, same problem occurred. So it was not that.

What can be wrong?