car wobbles at various speeds on 1994 Lexus GS300

My 94 gs300 rides smoothly, but after pressing the brakes firmly, the front end wobbles, at various speeds, but only for a short time. The wobbling is now happening more frequently. What could be the problem?

Asked by for the 1994 Lexus GS300
I would suspect the front brake rotors are warped. When the brakes are applied brake pads are pushed into contact with the brake rotors by hydraulic pressure. Its like the rubber brake blocks coming into the rim of a bicycle, if the rim is bent you get a vibration. Similar with the brake rotors if they are warped when the brake pads contact the rotor if they are warped the steering wheel and or brake pedal will pulsate when the brakes are applied. The brake rotors will need to be machined or replaced.
1 more answer
Have you checked your BUSHINGS in the front? Bushing is the padding between the many different suspension joints. I have a similar porblem in the rear and it was WORE BUSHING.