Hi everyone! I hope this doesn't offend anyone as this is my first post and I haven't had the chance to contribute anything yet to the group (I was referred here from Benzworld). I am the very proud owner of a 94 S500 that has had the following idle issue since I picked it up about two months ago:

When cold, the car will respond to the throttle to approx. 1000RPMs and then will act as if the fuel is being cut off or it is hitting a rev limiter. It bounces between 1000 to 1600 if I keep the throttle floored. Occasionally it will "catch" and run up to 3 or 4k RPMs but only for a second or two.

When the car is acting like this, there is a different tone to the motor, almost like it is wheezing, there is a higher pitch quality to it and it sounds anemic. When the motor catches and when it is running properly, it has a much deeper sound quality to it. (I don't know if this is helpful but I'm giving all of the info I have.)

Up until last week when I started playing with various components on the car the ASR light was NOT on regardless of operating condition nor the check engine light.

The above symptoms would only occur until the vehicle reached normal operating temperature and then all would be fine. But the temp needle has to be on the next mark above "80" (I'm at work and the car isn't here so I don't recall the numerical value on the gauge) otherwise the symptoms persist.

My 94 still has the LED diagnostic code box in the motor compartment and nothing comes up when pressing the button. I am at a loss since there are no codes and I am not sure where to go from here. I am afraid to take it to the dealer as I assume they are going to assume the EA is bad and recommend replacement. If it truly is the problem then I will replace it but I am not convinced since I have read every thread I could find in regards to this and none have quite the symptoms I am describing. Also, once the car is warm it runs beautifully.

Any advice will be greatly appreciated. A solution would be great but I am really just hoping to get pointed in the right direction. Maybe someone with more experience than I have can shed some light on this?? Thanks for any and all replies!