I asked Mark at Abbey Motorsport about all this business with the throttle.
From what I remember, the throttle position is monitored by the ECU at all times (even when the car is off). It has two permanent lives and earths. Because of this moving the valve upsets the sensor and actually burns out the ECU. If this happens you'll have to have the ECU repaired as resetting position will make no difference.
With that said, to avoid this disconnect either the battery (what I did when cleaning mine), the throttle sensors, or the ECU. Once that's done your all good to clean it