This removes the dampers, and the crossover / equalizing tube.. What is causing the stumble? Not really sure, some say it's the Fuel Rail. Nevertheless, this makes the system act just like the GD which didn't have the problem..
If someone really throws a damper into the system, Standard Motor Products FPD71
Fuel Damper Assembly is around around 38$. Needs to be installed on the "FEED" line which is easy enough to add. For something German made, check out the Bosch #0280161037 but it's pricey.