Maybe was the OVP relay
The day after I had the stalling problem I swapped OVP relays with my wife's "92 300e and my car has not stalled since. Maybe it was the OVP relay. I was not getting an ABS light or any other symptoms and my wife's car is still running fine with my old OVP (I was really hoping it would stall so I would know the problem for sure). Maybe the OVP is bad and her car is just more tolerant.