96 850 NA fuel damper
 

seems nobody has this part Bosch W0133-1660728,can i disconnect it or plug vac port? leaking fuel out vac not holding fuel pressure when shut off

Did you try calling a Volvo friendly parts store like FCP Euro or EEuroparts? Also try calling Tasca Parts as there may be an OEM parts replacement number change. Have your VIN handy as there may be a difference by chassis number.

I don't know how they work. If it has a vacuum port, then evidently there's a diaphragm in there moving in response to not just fuel pressure but also manifold vacuum. That makes a ton of sense for a regulator, but they're calling it damper. I don't know whether you need it or not.