I am sure this has been asked before but I don't feel like digging for it so I'll just ask it again. When you idle, are you on 4 or 8 cylinders? Any time I've asked salesman or other people at the dealership, they always give me the same line. "MDS activates under light acceleration" and they never answer my question. I would think it would idle on 4 because you aren't accelerating at all.