AVF Random boost problem

Hi peeps! I've been mostly just reading but DOH, this problem certainly need some help from yall.

My AVF 130 bhp -03 Passat variant boosts randomly: sometimes it works like it should, sometimes it boosts past 3-4k rpm (or even higher) and sometimes it wont boost at all. Restarting doesn't help at all.

I had codes for fuel temp sensor and MAP wiring and after I fixed those and cleared codes my engine light went away but the problem still exists.
I did replace all the vacuum lines, N75 (due broken nozzle), clean and bypass the EGR -system http://uk-mkivs.net/topic/50427-pd-vac-line-simplification-n18-n239-valve-delete/ clean every sensor and did the mr.muscle trick twice (tho I'm not sure if the foam got to the turbo since i put it in from the EGR pipe.)

I had emissions and engine lights on, but now they are gone, no new codes.

I'm getting a bit desperate.. any ideas, tips or tricks I should try?

It seems there are 3 of us with that problem.

My take is it may be the boost mechanism in the turbo not working.

I have to take a look, possible vacuum leak but any sticky is going to be an issue.

That's not a lot of force its working with.

Ok, as best I can, while I used to work mechanics, I am mostly out of it and that was before we had VV (variable vane) turbos.

So this is not intuitive to me.

The Diesels use a vacuum system (maybe gas to?) and there are a number of parts that can go wrong and different symptoms involved. That's where I get twisted up.

Max takeoff for an prop aircraft with a variable pitch, the pitch is flat. You would think you want to grab max air, but what you want is the most speed and flat pitch provides that.

If you listen to a Floatplane taking off, it literally is screaming as it starts and then once off and up to 300 feet or so, you hear the tone change dramatically.

Something of the same is going on in the turbo.

Areas that can be an issue.

1. Back check of some kind, black and white as I understand it that can plug up. Intermittents .

2. Then there is the N75 which controls the vacuum per ECU.

3. Pot that moves the turbo mechanism

4. Mechanism itself.

Still trying to figure out what the default mode is, too much or no boots.

Any of those items and the air lines can be a problem.

MAF can as well and may need re-connect on the plug (or cleaned)