Over the winter my boost backed off to about 10 psi, I figured the spring maybe fatigued but didn't care because lower boost let me run 91 to save a little gas money.
Anyways, spring rolls around and I turned it up again... nothing. Kept turning it up, still nothing. Took the MBC apart and it looked clean, wiped all the parts off and cleaned it with some solvent, reassembled, and she works like a charm now.
Clean your boost controller out, I was real surprised at how little dirt it took to keep it from sealing up tight and working right. *for clarifications sake it wasn't dirt per say, more like oily film from the valve cover vent, which has been disconnected for quite some time.