Well - checked vac supply at "T" from brake booster - engine running = 19 inches. (However - did not "jump" up to 19 inches - took about 1-1/2 seconds) Then checked line from white valve on IP, = about 19 inches. Then checked with throttle movement - 1/4 throttle - CLICK at switch over (on fender near black piece that feeds vac line to EGR AND recirc valve on turbo) when CLICK happens (1/4) throttle, vac jumps down to about 10 inches, then goes back up to 19 slowly. After that at 1/2 throttle no change in vac. Do you think that this switch over (3 way) valve is to blame? If I take electrical connector off of this valve - vacuum does not drop at all.