Any suggestions on getting rid of a slightly rough idle? Car seems to be a little rough in gear at a stop, I already changed wires/cap/rotors/plugs, and ran through a few quarts of Techron - no change. Car has very low mileage but I can't get it as smooth as I'd like.

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2003 S500 Black/Charcoal
1990 560SEL 61k Arctic White/Grey

SOLD:
1988 420SEL Black/Palomino Sold @ 85k
1987 420SEL Midnight Blue/Grey
1986 420SEL Diamond Blue/Grey
1983 380SEL Champagne/Palomino