Warped discs! the reason your steering wheel wobbles is because the Discs are like a buckled wheel and the force from the caliper pistons is causing the wheels to follow the discs warped fashion! Reason being you've been braking too hard and and getting them too hot.

Are they Drilled? As any cooling will help, alternatively brake sooner you LOON or use your gears more.

If the Pedal pulses up and down when you brake then thats a pretty good sign your drums are ovaled!

Remember Drums are better at braking than Discs but they are NOT as efficient and get too hot too easily. When was the last time you adjusted the shoes?

If your discs are getting that Hot you could do with some high boiling fluid (If you havn't already)