Sounds like your ALDA is broken. Although it's common to adjust it for increased power off idle (it doesn't increase top end power), I've heard that about 10-20% of the time the internal diaphragm breaks and renders the unit useless. Mercedes does not sell the ALDA separately. You can try to find one at a junkyard, or try to buy one from a Bosch repair shop. It just unscrews, hold the brass nut underneath and turn the whole ALDA 'ccw' to remove it.<br> <br> <br> Good luck,