I was wondering (before I replace everything in site) possibilities for this scenario:
Lately its been cold and I've noticed that when my car (1986 560 SEL) is cold,she idles fine, but by the time it reaches temperature, she runs pretty rough. Although its not really that noticeable on the highway, its starting to get terrible in my opinion on sidestreets and off the line at a line.Sort of like a slight missing and shacking type feel to it but once at about 50mph or so she's fine.I know this is screwing up my mpg, and I'm ready to start replacing replacing replacing and I'm eager to hear some suggestions in order of priority in you guys' opinions. thanks
(I've already replaced plugs done and no change in idle so far) she's got a bit over 216k miles and has treated me good but ever since we dropped to 30's and 40's she's changed a bit

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1997 E320
1986 560SEL
1983 300SD
1972 220D
1970 250C SOLD
1971 250C SOLD

Could be as simple as spark plug wire end or distributor cap. Secondary ignition system is the best starting place.

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Retired Moderator

Thanks M.B. Doc! I'm thinking of changing the wires too.. also,
where are the major "secondary" ignition components located specifically? Does that affect the idle changing once the car warms? It seems like on the highway 60-70 mph it surges but the throttle reponse is retarded and I was actually considering putting a high performance ignition sometime soon. What about the fuel distribution?

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1997 E320
1986 560SEL
1983 300SD
1972 220D
1970 250C SOLD
1971 250C SOLD