One of the most troublesome component in a 103 engine is a OLD and failing Fuel Pump relay . Initially it will be a occasional stall at a stop sign and progressively gets worse ,there is always a quick restart . Eventually it fails completely.
I had re-soldered mine, worked well for a couple of years then failed completely .
It can be misleading as a possible ignition fault.
the OVP does fail too but will not leave you stranded , one of the symptoms will be difficult cold starts and low RPM's at idle.
mak
300se