I can understand it changing with rpm, but why is the rpm changing by itself? With the sensor/eha removed the idle is stable and the car is tuned correctly - it drives great with no electronic control. It's been tested on a Lamba/CO2 sensor with everything disconnected and the duty cycle is around 40% slightly rich. Once I connect the sensor back up again the idle goes mad. In the factory CD it gives resistance valves for the pot, mine is showing infinity.