Front Brakes Problem!.. Streering Wheel

What up!.. I got a irritating problem with my 94 buick problem.. everytime im braking my steering wheel starts going right..

i already did the alingment..
balanced and rotated my 20 inch rims
changed the calipers which i told was the problem and its still doing the same thing

also when i go past 60MPH on the freeway my whole front of the car starts shaking and my steering wheel does to.

anyone have a clue on whats going wrong??

thanks!

Before or after the 20' tires number one number?. 2 has any body checked that the calipers apply, wheels off the ground. Wheel shake at 60 is a bad balance, rim or tire. The entire frt suspesnsion and steering must also be checked for wear or looseness, this all basic diagnostics.