I am still trying to nail down the problem on my 1986 300E. First, it is hard to start when it's cold. Now the "Check Engine" light comes on after I get it started. The funny thing is that it turns off after I get going for about 5-10 minutes. Once the car has warmed up to 80 -C it idles high, and therefore is causing a rough ride at red lights. The car rides great on the open road and shows no sign of smoking, leaking or stalling, sputtering, knocking, rattling, shaking, pinging, back-firing, or downright ugliness. I have replaced the spark plugs, made sure cap and rotar are in good shape, checked the wires, they were fine. Replaced the air filter, put on new tires (hey, after hearing about the cruise control issues I thought I better include it) gave it a nice wash job (just in case) and named it Betty. Anyone have an Idea on what I should do next?
Saul Goode
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It probably has to do with your fuel filter, fuel pump, or dry rotted hose. I have the same problem with my 1987 300e, it has trouble starting and it will just shut off when it is cold and i've been driving for about 5 minutes. I suggest letting it warm up until you can get the hoses checked.
Rough running 124/300E 
Linear Mode
