DHB,
I think that test only confirms the vacuum part is operating correctly. There are two bolts holding the EGR valve mess on the intake manifold. Take out the two bolts, slide the specialized gasket in descibed above (I made several out of roofing tin), put the bolts back in and tighten. Test the car in that configuration a day or two and see if it stops. If it does, you can replace the EGR valve or just leave the special gasket inplace until you get "Round Tuit." Until then the only thing you need to make sure of concerning vacuum to the valve is that it doesn't leak vacuum. I accomplished this with a discreet replumbing of the vacuum lines, which when reconfigured, somehow didn't supply vacuum to the EGR valve. (Someday I need to take these cars into a dealership and get that fixed
)