Audi Brakes Dragging Intermittently

[Jeff May <jeffmay@pcnet.com>]

I have a 1987 TQ.  It has 140,000 miles on it.
It is well maintained and (obviously) a daily driver.

My problem is that when the weater heats up or the engine
compartment gets hot because the car is sitting in traffic.
The brakes will start to drag.  This I feel is not safe.
My local dealer is mistified.  He has completely bled the
the brakes, checked for stuck calipers, check the pressure 
accumulator, replaced the power steering/brake pump,and replaced
the emergency brake cables.  All in vain.  Of course now we are
in the cooler months, it generally will not occur.  Yesterday
for the first time in a month I was stuck in a one hour traffic
jam and it did it.  When I finally got free and was back up to
speed the problem slowly disappeared as the car cooled down.  
I want to add that when the blasted thing does it the brake
pedal has a harder feel to it.  I mean by this that normally
it has a softer pressure that increases as the pedal is 
depressed.  When the brakes are dragging, the pedal loses much
of its softness and feels harder to depress although it does
not seem to require much actual force to activate the brakes.

Any suggestions?