In my '88 190E 2.3 with 154K, I have a very low idle (~500RPM) which stalls
the engine at times. There is dark (not blue) smoky exhaust (with sooty
deposits) but on the highway (higher speeds) everything works well. There is
no oil leakage anywhere (on the ground/around engine) and no blue smoke. A
friend mentioned that the 'idle' setting is 'low and rich' and the 'remote
sensor' may be at fault.
Any comments, caveats, cures, etc... most welcomed.