I have the same problem with my 500SL, getting worse with time. There have been numerous posts by people all over the world involving many Mercedes models built between 1990 and 1995, that use a similar ASR system. This is a poor design which Mercedes do not admit to, and my local dealer service centre told me that they haven't seen this before, which I don't believe. I am told that because my car is a 1990 model, the computer diagnostics don't remember the fault, and trial and error part replacement is the only way to fix the problem. Is that correct? The only thing is that most of the parts are outrageously expensive. Would any one know which parts are the most common to malfunction in order from most frequent to least, so that I can start the trial and error replacements.