warning lights on my xtype jaguar?

i have had a diagnostic done by a local garage on my xtype jaguar 2.5 2001 and it shows a problem with the throttle response sensor. the mechanic reset the problem and my car can work perfectly for weeks then without warning the the amber fault light comes on followed by the limited power light. If i let the car cool down the amber light remains but runs ok.the last time the amber light cleared by itsself