Engine chug with new transmission

[2G95tsi]

I just put a transmission in my car and now at 3 plus rpm it has a huge engine chug then it's back to normal, but it only happens when my foots all the way down in the peddle, my boost is also being a little sketchy where should I start looking to fix the problem?

 

[TwoLiterLaser]

What exactly is the boost doing?

You could a boost leak test. And are you still using the stock boost regulator solenoid?

 

[2G95tsi]

The boost is really low in first and second gear and then it hits about 16 and chugs, yes everything is stock