I am trying to sort out the hesitation issue on my 2006 1.9tdi, it only seems very slight and happens several times when accelerating hard between 3000rpm and the redline. I have read  a lot on here and some posts mention the fuel filter, I have tried to find the fuel filter but the local motor factors say there are 3 listed and didn't know which it was. I also read up on Maf issues so thought I would try disconnecting it.I took it for a spin with the maf disconnected and the car feels so responsive, it revs so much smoother but the hesitation is still there at high revs. I also put £20 of premium diesel in on top of a low tank. I got an engine warning light the day after I bought it so bought a handheld scanner and it said originally EGR insufficient flow and no 3 glow plug open circuit (tested with multimeter and it is dead so new one on the way)  I have looked at the egr and cleared a bit out of it without taking it off but to be fair it didn't seem to dirty really, maybe a 5mm coating of carbon on the worse section I could see which I removed with a blunt knife and vacuum cleaner. Code reset and has not returned so hopefully that's sorted for now. Should I be looking at replacing the EGR, Maf and fuel filter? Thanks

The best thing I did to improve the top end response of my engine (PD170) was to remove and clean the intake manifold @ 100k miles. Reduced gas flow may not be soley due to a dirty EGR valve. In my case it was a dirty EGR valve and manifold immediately after it combined that caused the problem.