Turbo overboost?

[JDR33]

Hi all,

I seem to be hitting different obstacles lately with my mk4 golf 1.9 tdi ARL. It's really doing my head in.

I think I may possibly need a new turbo but I've never owned a tdi before now so I can't really know what the tell tale signs are without a second opinion.

I've noticed lately the oomf has gone so I'm struggling to pick up speed until around 2k rpm then the turbo comes in to play but doesn't perform like it used to.
I've had a morning where I've jumped on the motorway and the cars completely lost power to the point where I had to pull over and start her up (then runs fine).
Then I have days like today where I drive back home taking it steady, come off my junction and get to the lights, then all powers gone again.

To explain it, I struggle setting off with a change of note in the exhaust (loud thumping sounds). There is no turbo power or whistle. When reversing In this mode the car is easily prone to stalling. I turn the car off and back on it runs normal with the turbo. I do hear a whine sometimes from early gear changing but only brierley not sure if related?

I've looked underneath, have seen a fair bit of oil all over the turbo and surrounding areas it could drip down to. Cat and exhaust seems fine, intercooler just has light misting around the connecting points.

I do have smoke sometimes upon start up but mainly on cold mornings.

Could I be looking at replacing it shortly? I don't have vag-com to check and i don't know anything about it anyway.

Thanks.