[V8] ABS Problem?

[Jeremy Ward]

So I drove to work today and the car was behaving itself.  Got in it at
lunchtime and the (parking)brake light never went out on the dash.  This can
sometimes be caused by low brake fluid, so I popped the hood - alles gut,
brake reservoir was full.

Car seemed to drive normal at first, but after stepping on the brakes a few
times, the brake pedal started to shutter (like when you dynamite the brakes
and the ABS kicks in) and stopping distance was greatly increased.  If you
are sitting at a stoplight and press down the break pedal 'extra good', it
shudders then too (but not when you are holding your foot at a normal
pressure).

Tried turning off the ABS switch on the dash - no difference.  Checked all
the fuses - good.  Pulled the ABS relay - its fuse was good and the orange
AntiLock Off light came on.

I am able to pull into parking spots OK so I don't think it is locking the
diff...  (that is a telltale sign of an ABS sensor, right?)

Any ideas?

Thanks in advance,

- Jeremy