blender

first post so i hope i am doing this right, i have a 99 ls400 which is perfect but over the last month i have a vibration when brake pedal is pressed when braking over 25mph,the vibration is felt through the pedal,local garage has checked everything and even had it on rolling road and it is perfect, pads are good and no warped discs,checked all joints and bushes but cant find anything, he and myself at loss to what is causing this hope someone can help me. thankyou