Hi recently my 08 d40 have been losing power when traveling on the highway . The engine will still rev but very very slowly but all power is loss if I get back to 4 th gear 90% of the time the power with come back in the other times I have to pull over don't have to turn the car off and it's good to go . In a 400 km trip yesterday happened about 7 times . I have changed a fuel filter about 3000 km ago and also reset fuel curve or something . Could this maybe be the issue ..?????