Hi my 2.0 hdi 407 seems to be slow in upper gears only. It's fine driving about town in lower gears but getting on to the motorway it seems to have no power in 4th 5th or 6th. Any ideas? It still gets to high speeds but takes an age to get there and really struggles with hills on the motorway to the point where I may have to change down. I have checked and replace the airlines going from the intake to airfiler to MAF then into block and they are now fine and properly sealed (there was a crack in a pipe before...) but that doesn't seem to have solved the problem. To explain the symptom more I go onto the motorway, put my foot down in 4th say and it pulls away fine up to say 2k revs then it's like a massive dead spot. I put my foot down more and nothing happens.