Detailedpaintersllc1

Looking for some help as my 2002 s4 will not hit above 5psi now but before 16 psi. Intermittently for weeks it would hit only 8psi but then not long after be back to normal. I wouldn't think it's a boost leak since it was so randomly going back and forth from being fine to not. I have now changed my n75 valve and no results. It shifts into second now but bogs Down right after shifting only for a second but still won't build any boost. Any suggestions would be appreciated.