From what your saying I would almost bet it is the rotors. When I purchased my 97 Aurora it also did just what yours is doing and it was the rotors. This is a very easy do it your self fix if your so inclined. All you have to do is remove the the front brake pads and calipers and the caliper mounting brakets and the rotor will come right off. A good set of front rotors will run you about $90-$120 each depending on where you go or you could spend $30 for the elecheepo at Advance Auto or Auto Zone.
BKVic