P0427 and P2080 on Ford Focus 2.0 TDCI Duratorq 2005.

Question

The car will misfire/hesitate slightly after P0427 shows and quite markedly when P2080 appears. When codes are cleared car will run well until codes are thrown up again within a few minutes or less. It has on two occasions given me P2263 - Boost Performance DTC when it was being driven fairly quickly 70-80mph. It has also stalled twice at idle when P2080 showed. Anyone recognise these symptoms. First I thought maybe the Exhaust Temp Sensor but now wondering if it might be EGR valve sticking.