flyboyles

Hi all I'm looking for a bit of advice please
I have a 2006 A6 Allroad 2.7 tdi auto it's started about 2 weeks ago when I pulled out of a junction and I had a loss of power and the glow plug light stated flashing, I plugged it into the small hand held obd reader I have and it come up as P2002 DPF Efficiency below threshold bank 1.
So in the time I started looking for a company that can plug the cleaner into the DPF I put 2 bottles of cleaner in the fuel with no joy and I've been running it back and forth to work 30 miles on the motorway to burn it off with no joy, But on the way home i stopped off and parked it facing up hill for about 10 mins got back in to drive off and all was great i had full power back until i got on the flat and back to low power and flashing glow plug light I turned around and done the same again and back to full power until on the flat.
Please has anyone got a clue on what to look at ????? I've been thinking could it be a fuel filter problem or oil in the auto box ???
Thank you for your time to read about my problem

Razor B

Not that I have a lot to work from, but you may have a piece of plastic or paper on the bottom of the fuel tank that's blocking fuel flow when it gets in front of the screen. Do you have a way to check the fuel pressure?