190e occasional stalling - please help

My 1984 190e occasionally stalls. It stalls hot or cold, wet or dry, day or night, etc. Sometimes it stalls 20 times in one day and sometimes not at all. It stalls when idleing and it stalls when driving, even on the highway. Sometimes it starts fine, but sometimes it just fires and dies right away. When it stalls it seems like someone just turned off the key. When it runs, it runs great, no chugging sputtering etc. Any help would be much appreciated of what to check. Someone mentioned a "Hall sensor" whats that?
Thank you very much Bob Crowe