Ok I will try to fully explain how I changed OEM pcv system to my catch tank system.
from this part near oil filter:
goes a new hose directly to mycatch tank open
this is the place on my car:

this is my catch tank with 3 opens:

second tank open on the side goes directly to valve cover
and the open on the top of my catch tank goes to to "hockey puck" valve that goes to TIP.
this is the and of my pcv system. It is a fully closed system.
Oh and open under inkake manifold from valve that gone to oem pcv valve is closed now.
Hope I cleared the situation

Also this N's system is out:


now dv is connected via hose directly to intake manifold.
I also have cold side dv relo kit

thanks I will try it today.
Should I first reset ecu to get 0% in LTFT before I start this test ?
Or should I do it with my LTFT on -18% ?
or maybe it doesn't matter at all ?

Ok I explained my changes in pcv and N's systems, so now my dv relo kit.
Before mod OEM dv place was like this:

after a mod this is a new cold side open for dv:


2 orange hoses are dv hoses,
one to new open on cold side, and second (the one you have asked about goes to second open on TIP - the same open that OEM)

black small hose goes directly to intake manifold (OEM open under manifold)
full dv sestem:


oh, and dv is a new forge 007 for mk1 TT
I was using OEM dv when my setup was fully OEM,
when I started mods I changed OEM AUdi DV to forge DV.
I never used BOV - in my opinion BOV is a bad idea for 1.8T engine

I'm reseting ecu and adaptation valies from time to time.
Usually when I want to test some new idea to deal with the problem or want to do some new logs
So I can say I reset it when I change or swap some parts that can be a cause of the problem.

of ane ONE MORE VERY IMPORTANT INFO for everybody:
I have this problem since I bought the car. Ihe car was full OEM that time.
I started changing parts to new and mods slowly always checking it the problem is getting better.
But nothing good happend since that time.
So my point is. I'm 100% sure that
THE PROBLEM IS NOT CONNECTED WITH ANY OF MY MODS.
But of course this is only what I think and checked so we can argue about it
Feel free to any new ideas.
I will check o2 sensor using test in link you gave me and hockey puck using test you described.

He said he bought this car with this problem, Now I'm thinking maybe the tune, and or lemmewinks.

I don't think that car was tunned before I bought it.
I did logs after I bought car and values were stock.
I also was on dyno after I bought it:

+ I added my ecu file in this topic as attachment - so you can check in I'm right

maybe I am blind but I don't see your ECU file attached anywhere.

found it..dunno how I missed it..

I will check it out I think I have a definition file for it maybe.

If the fuel trims are positive on short term and  negative on long term i have seen many bad mafs cause this issue. even with out any faults other than rich.

You can drive without the MAF indefinitely. The ecu uses a calculated value sans the MAF signal. If it were me, I'd flash a known stock file (yours doesn't look stock, if the car is rated @180hp that's a crank figure, you're showing 179 at the wheels?) and keep the MAF plugged in. Verify it's the correct MAF (notjust the housing, remove the sensor and verify THAT is correct). I don't think your trims are due to a leak.

I'd bet thats a tuned file, that surging is classic for poor tune.  I say leave everything the way it is and flash a known stock
file.