Hello

Got a P16500 code on a audi A5 2.0TDI. Car shakes on idle and when holding revs up the shake goes away. In live data i can see fuel pressure at idle jumps a lot under the 250000 kpa specified and when holding revs it sort of jumps as well but the shaking goes away.

What i have tried already to fix:

1) replaced fuel filter as its cheap enough to elimate.
2) checked injector deviations and they seem within range of each other, have removed the plugs with engine running and the shaking gets worse for each injector, no smoke out exhaust and when revving shake goes away leading me to believe injectors are fine.
3) removed fuel metering valve on the HPFP checking for metal shavings and none present
4) I looked at the fuel rail and this looks like its already been replaced but i don't know for certain so how could I be sure if its been replaced.
5) I have replaced the fuel rail pressure switch i think its called (the one you can see from the front of the engine going to the rail) I had same part number laying around so thought worth a try.

The label on the rail looks like its new but theres a date on it that says 25/06/2009 and the car is a 2009 so my question is if you buy a genuine replacement part from Audi in 2025 would the date on the part be from 2025 or 2009?

I havenÂ’t replaced the rail yet due to it looking new and don't want to play parts darts so if anyone can help would be great as not sure where to go from here.

Thank you