Impreza Manuals | ken-gilbert.com
I don't know how much they will help because I think you vaccuum lines have been modified from the stock setup.Probably due to installing a turbo inlet or catchcan.Take a bigger picture(zoom out) of the engine/vaccum lines.You to close up to tell in the picture where things are going.I would try bleeding the clutch as well or if you did you have not pumped it up enough.
