Thanks for the great thread everyone.  I'm the original poster

When I slam the pedal to the floor I can't get my wheels to lock up.  That
the bad part.

Here are the additional things I have checked now.

Need some help with my spongy feeling brakes.  Here is what I have done.
-Replaced front brake pads with metalic pads (about 2 yrs ago)
-Replaced master cylinder (last night)
-Bleed brakes using two person system, depressing the pedal and hold.  Open
bleed valve and close before letting off the pedal. Repeat 20 times per
wheel.
-Checked all break rubber hoses to check for bulging or expansion during
pedal depression.  (none)
-Checked function of vacuum check valve for brake booster in engine
compartment.
-I also adjust the rear drum brakes so the slightly drag.  Still no effect
on the braking feel.

The brakes are still spongy.  As I depress the pedal it increases in
resistance and then makes a tapping sound (like hitting metal) and then
depresses more.  The brakes kinda stop the van but when I slam on them,
it's a little scary, not producing a positive feel.  The brakes will not
lock up.

Here is what I think might be the problem:
-Front brake pads aren't set right.
-Not bleed properly.
-Brake booster needs to be replaced!  :(  I'm sure that's an expensive
one.  The diagnostic in Bently says depress the brake with the van off and
then start the engine and the pedal should sink a little.  It that happens
the brake booster is OK.  My brakes do this so I'm hoping that the brakes
are OK.

I hope that I haven't tapped all the ideas out of the list.  :)

Thanks for all the comments and help everyone.
Blake Heinlein
84' Westy.
Sacramento, CA