I have an 89 300se that had a very similar problem. Mine would as soon as you put it in reverse to back up, it would stumble and as soon as you hit drive, it would 3 out of 4 times stall. My MB mechanic stated that injector seals sometimes go bad and can cause this. I had them replaced and the car runs fine now. Hope this can be of some help. And it was not all that expensive, compared to the $$ you can spend on MB repairs. I want to say the seals were around $30 and the labor put it up to about $75-$100 range. I think I am correct in my memory. Scott