front wheels are shaking the car when braking

[34s2104]

lets start from the beginning.

when i bought this car (1996 318 ti) it was reconstructed was in bad condition.

when i was driving straight it was pulling left or right i dont remember exactly and while turning left or right it was shaking whole car very badly.
then i starting fixing the issues i could find. replaced right and left lower control arms, front brake rotors and pads, control arm mounting bushings, replaced 4 wheels and tires. i left it to a garage for alignment.

i asked to the mechanics there before alignment if i need to replace something else, they said everything seems to be perfect.

when i left the garage it was driving smooth. but the other day i realised one more problem.

the problem is :
you are driving with 50 mph, then you start to brake softly, it shakes for 3-4 seconds and stops shaking after that.

i m sure that rotors are ok. (i replaced them again problem continiues)
i m sure my tires and wheels r ok and balanced ( i have winter and summer tires with wheels)
i m sure my pads r ok ( i changed them several times but nothing changed)

and it feels like especially left wheel is moving back and forth when i start to brake and it stops moving after 3 seconds while braking softly.

any suggestions ? or somebody else having the same problem ?