N80 valve experts needed!!!

I find only a little info on this valve. Ive been having a problem with misfires and fuel cuts for 20000 miles now. VW today replaced my breather hose assembly and my n80 valve. I have no confidence in VW and I am skeptical this will even solve my problem. Anyway...

1. What is the function of the n80 and how does it function?
2. What causes them to fail? Could it be because of higher boost?
3. What are the symptoms of a failed one? (All I've seen is a ticking sound that goes away upon throttle)
4. What are the symptoms of a failed breather hose?

Thx in advance

I'm familiar with the N75 in 1.8ts and they evened out the boost ratio.

N80 is the evap purge valve. It's turned on and off (open/closed) by the ECU. I've read that particles can sometimes get stuck in them in the winter causing the valve to stay open and fail. I've read a failure in the valve can cause misfires.

When do you get the misfires? Cold starts? When you are getting on it in high rpms? All the time?

Used to be fuel cut only in 5th or 6th gear at like 3500-3800 RPMS. Then it misfired at idle. Now it constantly misfires.