So i've been chasing a boost issue for sometime now and thought I had it figured out and now its back. The problem is that I either build boost slowly and hold at 5psi or build boost quickly with no control over pressure. I cirrently had the N75 bypassed and the line run direct from the wastegate to the turbo pressure port so I shouldn't see more than 5 psi. I also removed and capped off the solenoids under the intake as the SAI is bad. All is capped tight and no leaks. I recently unplugged the MAF as it too is dying. What do you guys think is going on? Is it possible that the temp. Sensor could be causing this as I believe that might be bad too as the car doesn't always idle up at a cold start.

 

Throttle position sensor possibly, Gas related, bad dv.
Though with all the things you've moved around in the motor it's kinda hard to say. Not sure how your n75 bypass would work in your favor. Each time I've tried to get passed it, it doesn't work in my favor, unless I simply unplug the sensor.