My 2002 1.9 tdi 130 sport has had what I can only describe as a "flat spot or hesitation" when accelerating up through the gears. When you lift off the accelerator to change gear and then gently push down on the accelerator there is very little throttle response and as you keep pushing you suddenly get a big surge of acceleration. This has only happened about 5 times in the last 6 months, the symptoms appear to gradually ease towards the end of the journey (may dissappear within 5 -10 mins or last the whole journey and switching the engine off and on again does not clear the problem) but are gone the next day and may not appear for a couple of months. Has happened first thing in the morning and when going home from work. The car has 70k now and the dealer diagnostics didn't show any faults (apart from an engine mount error) when I had a new key coded 3 months ago. Can hear the turbo spinning up when the car is running fine and when this problem appears. Any advice greatly received.