87 5kcstq- Weird symptoms: hydraulic problem?

[Larry Mittell <lmittel@ibm.net>]

Two days running, my Q has had the following symptoms on my 52-mile trip
home from work, but not on my trip *to* work in the morning:

1)  After 15 miles of 80 mph driving + 5 miles of stop-and-go + another 5
miles of 80 mph, a front wheel shimmy becomes apparent through steering
wheel vibration. It *feels* just like a wheel balance problem.

2) The shimmy gets worse for the next 10 miles of 80 mph stuff, then goes
away, but braking now requires stroking the pedal almost to the floor, the
triangular brake warning icon in the instrument panel illuminates, and a
warning "PEEP" sounds off. Braking effort is increased, but not by a lot.

3) After another 5 miles of 80 mph and 5 miles of surface street driving,
between one stroke of the brake pedal and the next, the pedal is again at
the top of its travel and all symptoms are gone for the rest of the drive.

It sounds like a hydraulic problem to me, perhaps accumulator and pump both.
What's the collective wisdom of the rest of you Q heads?

TIA,
Larry Mittell
87 5kcstq