Front end wobble

I have a 1996 LeSabre. When I apply the brakes at speeds greater than 65 mph, the front end begins to wobble. Any ideas as to what the problem may be? There is no obvious front end wobble when driving at high speeds or normal breaking at low speeds.

Thank you

Check the brake rotors for spots, or corrosion, or wavyness.

I replaced the brakes, including rotors, calipers, and discs, approximately 10000 miles ago. Inspection of the front brakes indicates all is well with the brakes. The car has 42,000 miles on it.

Thanks