my 89' 240 is making some noise under braking. It's got ABS and new rotors and pads. Its like a metal on metal noise. And it only does it when my car slows below approx. 30km/h

If it only does it when you brake it maybe a shime or clip hitting the rotor surface. If it does it just coasting you may have the backing plate or plates bent and slightly touching the rotor. You may have to pull the wheels and recheck the work. Sometimes new pads can make weird noises when first installed but it might be good to recheck the work anyway just for peace of mind.