Change all your sway bar links... front and back. This will help with your stability.
Check the dogbone in the back and make sure it is good. Most of time, it would be bad if never replaced... may rattle and easily moved by hand. This is really critical for stability.
Steering... you overtightened your steering box. Go to bmwe34.net to learn how to do it right.
Most likely you need to replace your tie rods on your car.