I've noticed that my wife's 95 E320 has just recently developed a very slight rough idle and a knock on deceleration (more noticeable when cold). The car has been fully tuned up (it has 120K+ miles) and my wife swears that she only puts high-octane fuel in it. I also seem to notice more exhaust smell then usual (but this might just be because I'm paying attention to it). Could this be an indication of a bad air flow sensor? I have no check engine light indication.
Thanks,
Josh