I understand the problem was probably with the autothrottle rather than the engine
Rather a strange statement, let me explain.
The auto throttle drives the throttles>>> the throttle position (angle) is sent to the Fadec (EEC)>>>the Fadec sends demands to the fuel metering valves to give the appropriate power.
For the problem to have been due to the autothrottle system it would have needed a failure that, when power was demanded, only moved one of the throttles forward (which could have simply have been rectified by moving the lagging throttle forward).