Yes...the pedal pulls down as if a "ghost" was doing it. I've adjusted the rod 3 times and even set it so it was way too short, and then tried it with the master cylinder off the booster. It didn't make any difference.

Denny...I've been thinking that the check valve could be the problem. I'll check that some more.

Thanks for all the help/suggestions!! As always, I find a lot of help on this site.