i dont know if you have an active bumper or the sport m3 bumper but mine started to sag so i took of the bolts attaching it to the front then on each side of the fender behind the splash guard theres a plastic piece that the bumper slides onto thats connected to the chassis by 2 bolts. Tighten them both then slide the bumper back on and tighten the nuts on the front as well. The pieces on mine started to sag down and taht caused my bumper to do the same thing.
http://bmwfans.info/original/E36/com...1/ill-51_2395/ i believe its part number 12 in that diagram