560sl rough idle
I know there has been a lot of discussion on rough idle problems, but from reading prior posts I haven't seen anyone list the most common problems associated with rough idle on a 560sl. I know that some of the ideas are vacuum leaks, overload relay,fuel distributor, injectors, 02 sensor, ezl, air pump, etc.
My car has ~ $79k miles and I've replaced the wires, plugs, cap & rotor, fuel filter, and have used the techron cleaner, but no change.
The car starts and accelerates well. Even cold idle is ok. It's just once the car is warm and idling the rpm hunts in about an 60-80 rpm range. You can hear it hunting easy. I've checked for vacuum leaks using the carb cleaner method, but have found no leaks. The exhaust is a bit stinky so it might be o2 sensor, but don't know how to confirm? Also, I know there are a lot of electronic checks to perform on lambda and other controls, but only have a mutimeter.
Any ideas on how to proceed would be very welcome.
PS. Also have checked and cleaned idle control valve and egr.