Not Boosting Properly

[fozzysrb25]

hi all, got a new turbo put in ran fine for a bit then came up with a problem, it hit's 14-16 (tuned to 18) psi and the gauge goes crazy between them but it just doesn't pull like it used to. i took it back to the mechanics and they said it was a leaking manifold gasket and replaced that now it's starting to happen again a week later. any ideas? looks like i got powerfc syndrome as well so could it be caused by that?

[Burnz]