Granting IDK what the scales are but just looking at the data logging it appears that your manifold pressure isn't responding to throttle, which is a bit odd, unless BigAndy is right and you have another leaky hose that's shown up or a hole in the tank of the cooler.
I'd probably start pulling rubber hoses, check my clamps and clean all the plastic / aluminum surfaces with some serious degreaser, like brake clean. Ideally you would pull the outbound from the turbo and plug it, then plug the inlet at the intake, and pressurize it some to see where the problem shows up.
Is your red hose from the N75 to the turbo still connected? I replaced all my vacuum lines with nylon colored hose, except for the ends, on the red one the vacuum connection at the turbo failed after getting too oily and too hot I think. Replaced it a few years back with 1/8" fuel line, which is much more resistant.
Steve
Steve