I have gone through the ignition system, looked for vacuum leaks, and now suspect that the sluggishness I am experiencing with my '88 260E might be caused by an incorrect air/ fuel mixture setting or faulty EHA Controller.

I hate to play around with the air mixture because if thats not the source of the problem, I might not get it back where it should be and I know from experience that troubleshooting gets exponentially more difficult when you have two things wrong. Fortunately, I have a '92 300E that uses the same EHA as the '88. I plan to swap controllers and see if that fixes the problem.

Is there any adjustment required when replacing an EHA or are they more or less plug-and-play?

John