Shudder and Hesitation

Hi All,

Its been two weeks since my issue with my Audi A6 C6 Avant started.  It started to shudder and hesitate round about 1500-2000rpm.  My little VAG code reader said it was the MAF.  I bought a new one, a HAAS from Euro Parts.  I fitted it with excitement but the problem remained.  I then fitted a new fuel and air filter, still the same issue.  It was driving me mad!  I then took the new MAF back and exchanged it for a Bosch on, I fitted is with excitement as fixing the issue.  It was better but still the same.  

Then is disconnected the MAF, the issue then went away?  Less power, but the shudder and hesitation has gone with a slightly reduced MPG.  Because I use the car daily I have only got round at looking at it again today.  

Through reading I disconnected the Shudder Valve, Throttle Manifold Flap, whatever you want to call it.  I then drove the car a short distance,  it run really well.  I then reconnected the MAF but not the Shudder Valve, I drove the car a short distance, no issue whatsoever!  It drove really well.  I then reconnected the Shudder Valve and the problem was back with avengence. 

I have disconnected it again, so what's the issue, the Shudder Valve or the EGR.  I have VCDS arriving next week, I hope this will give some decent fault coding.  

Thoughts please.