Hi,
Probably the EGR valve solenoid is out. It uses to happen in this engine. The EGR is a valve located back to the intake box. At a certain rpm in a certain circunstances, the EGR drives exhaust gas to the combustion chamber again, in meaning of do not let the engine increase rpm too much fail the cylinder head by excessive temperature.
If you noticed an engine power decrease, and probably black smoke in the exhaust, the EGR failed in the ON position. If you noticed a truly life engine power increase, the EGR failed in the OFF position. In both cases, the engine warning advisor appears on in the panel.