I am a new member from the beautiful South Africa, and firstly would like to say Hi to everyone

I have an Audi Q5 3.0TDI and have been having a problem when driving 120kph and above, especially on uphills, where the car would give a pull back/surge/Shudder every now and again...Sorry this is the best I could explain the problem...I tried changing it to manual but still get the same problem. Audi have had my car for over 6 months, they have changed the gearbox, engine mountings, tyres, oil, oil filter, fuel filter, ecu mappings changes, changed diesel suppliers, used diesel 50ppm & 10ppm, used diesel cleaners, no faults reported on the system even when driving with the laptop plugged in and the problem surfaces...Is there anyone that has had a similar problem, or can guide me on what the problem could be as it looks as though Audi is running out of ideas on what the problem could be?

Thanx.