Hi David,
There is no "common weak point" on the D6. There is a number of things that could be happening here and we would need a little more info to be able to help. Some things to check would be to ensure that there are no leaks in the fuel system where the lines could draw air, and to make sure there are no blockages in the fuel lines. Check your fuel filter and drain a small amount to check for sediment or other visible debris. Also, check to make sure that you have sufficient fuel available. I know, it's an obvious question that I'm sure you already checked, but it still bears asking 😀
Hope this helps a bit.
Thanks!
Ralf