been having a few problems lately with my brakes on my 1986 90. basicaly what happens is at random times in a journey the pedal will go down to the floor and then next time be solid and normal. you never know when its going to do it. ihave replaced the master cylinder, bled 2lts of dot4 fluid through it, all the flexi's are stainless goodrich,pads are 6mth's old, shoes the same, all the pipes were replaced a year ago. the old fluid was black so i though master cylinder. i'm not loosing fluid just pedal pressure at random times. all thats left is the servo?? would this be giving me the symptons i'm experiencing?