I'm a proud owner of a lovely '91 2.3 190e, which I purchased about a month ago. It is a very fine automobile, but it has a strange problem with the idle and acceleration.
When warm (just a couple minutes after cold start) the idle starts to hunt up and down between 1000 and 500 rpms, sometimes stalling when it drops below 500. It idles steady around 800 RPM's in gear. It also tends to hesitate during acceleration at this time and I seem to be running rich.
I have replaced the O2 sensor, plug wires, cap and rotor, plugs and fuel filter, but it runs the same. I've heard that the coil on these cars can produce a weak spark, but I'm getting tired of throwing parts at this car.
Does anyone have any experience with this sort of issue? I've already searched through the forum and have not found any posts with the EXACT same problem.