what im saying is test the vac lines any way with carb cleaner while moving them up and down or wiggling them, as the ends crack. sitting still at idle the leak can hide, move the lines, and bam, leak area shows up. spray he solenoids also. anything a vac line plugs into.

theres no one way valves in the vac lines. on the boost solenoid there should be one open vac port, its supposed to have a little foam filter on it, but they fall off.