Stumbling Problem

We got the intercooler hooked up. It is a front mount from ebay and we welded all the pipes similar to Stinger's set up. I have a Bosch by pass valve after the turbo outlet plumbed back into the VAM flow into the turbo---that is at an angle to mix better with the VAM air. I have no boost leaks in the welds and all my T bolt clamps are on securely.
The problem I am having is when I shift. It will give a stumble or two when I shift and try to step on the gas. It's also like a pop too---not a backfire, just a little pop. Sometimes it does it and sometimes it will run fine. I think it's mostly when I step on it a little harder like getting on the highway or whatever.
Also, I am boosting 15 pounds but it feels like the boost is going somewhere else other than the motor. It sounds good and everything but it doesn't feel as though it has the power it should between 5-10 psi.
It didn't do this until we put the intercooler on. My VAM was acting fine and my fuel pressure was a bit higher than stock. I do have a big throttle body and the stock TPS is held on with a hold down bracket---could the cooler air be effecting the fuel mixture and maybe the TPS has moved under that bracket and now it is finally screwing with me??? I dunno...

Is the BPV installed correctly? Any chance it's backwards?

The by pass valve is the correct way. I went out to check on the car last night and the first thing I checked was the TPS. Come to find out it was set at .60 volts with the throttle closed. So I am guessing that the low voltage is my problem.