Another quick Q. Can I just remove the vacuum line from one wheel a time to separately test both wheels ? Ofcourse I will have to cap the line so it has good vacuum going to other wheel .

 

Yes, it's not rocket science by any means, sorta time consuming if you've never done it. I set aside about three hours, although it shouldn't take that long. You have to remember, I'm an olde guy, and I "WILL" take my time!
Just keep that bloody impact 300 yards away from that spindle nut, it only requires 30ft/lbs, very easily done by hand with a 3/8" ratchet.

 

Pull a vacuum on the downstream side of the solenoid. If it doesn't maintain, go down to each IWE and pull a vacuum there, that will help isolate where the leak may be.
If IWE checks out, you could have vacuum leak with a hose/line leak.

 

I have noted all the information above and I will take my time. No IMPACT wrench. I have all sorts of good torque wrenches since I do work on my motorcycles . Hopefully these checks addresses my issues