53 plate kia sedona 2.9 td?

my car cuts out now and again when im driving short distances. the engine management light comes on, then i lose power for 1 second or 2. i dip the clutch and change gear then i get full power again. the car drives great apart from this. ive had it checked on the diagnostic computer at my local garage and there was no fault picked up. does anyone have any ideas what it could be? many thanks