There is not any ECU fault. When the connector of the temperature sensor is connected, the injectors spray excessive gas and it makes the start hard and also causes an unstable idling. But when its disconnected the amount of sprayed gas is normal. I've tested the temperature sensor with the factory datasheet and it's working within the specification.So the problem is not a faulty temperature sensor.
Update: "Can you explain how you know that the gas is normal when the temperature sensor is disconnected?" Good point, maybe it's not ideal but disconnecting the temperature sensor makes the start and idling almost fixed.
"How do you know that the gas is excessive with the sensor connected? Are you sure it is not too lean? Please update your question" Because the spark plugs becomes wet with gas and when the spark plugs are dry the engine start in milliseconds, but then goes to bad idling and mostly it stops immediately.
"was obd2 in use then or after Jan 1996?" my car has 10 pin ALDL connector.
Any advice is really appreciated.