Current Sensor ACS714 Wandering Values

Using Arduino Sensors
2

I see some problems with points and commas and floating point and long and int.

Your calculation seems good.
Could you try a floating point calculation ? That is easier.

int sensorValue;
float milliAmps;

sensorValue = analogRead(analogInPin);           

Serial.print("raw sensorValue = ");
Serial.println(sensorValue);

// Convert to milli amps
// The offset of 512 has to be determined, perhaps during startup.
milliAmps = ((float) (sensorValue  - 512) * 5.0 / 1023.0 ) * 1000.0 / 66.0;

Serial.print("milliAmps = ");
Serial.println(milliAmps);