Replace DV to 710n
Did you use a screwdriver or something along those lines to remove the old DV and possible tear some of the hose down there?
Did you verify the valve was working correctly when you installed it? ie, push the piston down with your finger, plug the vacuum hole and release the finger on the piston, and it should stay. Release the finger over the vaccum hole and it should spring shut.
The 710N is what I use and I hold 20 psi with it and much more airflow than you, I'm betting unless it was a used part that could be bad your issue is related to install.




