My 04, A4 Tip is having some issue(s). I am getting a pressure drop between the turbo and throttle body+lean. The shifting is in the pot since the car revs too high before shifting into next gear. It has been smoke checked twice, TB has been cleaned+aligned, and tranny reset. NO VAC LEAKS. Cleaned the MAF and it did not seem to make much of a difference. I have not tested the "n75" solenoid or the MAF. I recall reading you can check for resistance to guage this(?) On the highway when I hit it with some gas you can hear the infamous 'dentist drill' sound and air rushing. If my "n75" solenoid is bad it might explain the somewhat normal opertion initially, crap performance once the car is warmed up, and the wastegate possibly being held open causing the car to have to rev to get the right boost to kick into the right gear creating the whole problem. My independent mechanic (with about 25 years of VW/Audi experience) feels it might need a new TB. What is everyones input?