the cold start injector is activated for a short period during a cold start ,so check its voltage while someone starts the car.
A low idle RPM with a starting problem point to a fault in the OVP : over-voltage regulator , this powers the cold start injector and the idleing speed along with other circuits
a common fault with the OVP is the fuse or solder joints going bad. Best replaced due to its age fatigue.
mak

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