Put on new turbo, weird problems, please help.

[9d1gsxintx]

I put in a t3/t4 turbo, that I had running about a year ago on my other car. I got everything hooked up and immediately ran into some issues. Well mainly my other car is speed density with running on an Electromotive TEC2, so I had the problem now of getting the MAF hooked up to my 3" turbo inlet. I got it hooked up but the nipple on the pipe I used is much smaller for the BOV return tube so I modified it some and will weld a bigger one eventually. But the problem seems to lie in that the car idles and runs fine, but when I take it out, it get about to second gear and when boosted it falls on it's face, and the boost guage is showing a constant 7psi with no peddle at all, I then have to baby it to get it back home. Almost like the turbo is just not responding properly or wastegate is stuck open, or not getting the proper vacuum signal although I have changed it several times and it was working on my stocker turbo, it has been a year or so since it was run, and has an HKS wastegate welded to exhaust housing. Thanks for replies.