Loss of power with steady acceleration. Safe mode??

My outlander loses power when I accelerate to overtake. Loss of power starts around 2500 revs, drives normally most of the time but when this happens it feels like there is no turbo working. Drops speed to around 60mph each time. No engine management light present and it resets itself if I pull over switch off and back on again.
Any ideas? No fault displayed either as just been serviced.