I found this part in trunk of 03 X-Type. I bought this car used so
I don't know if it even belongs to this car. The plunger has a
stiff spring when pushed down. It has a small hole in bottom but I
cannot feel or hear any air or vacuum.
Thanks.

 

that is a broken bump stop for the trunk lid. they attach near the base of the arms that hold the trunk to the car. they seem to be a common piece that is easily broken. when i got mine (second owner) there were 4 broken stops in the car and 2 working, although nonw were on the trunk lid. i put the good set on and it actually prohibited the trunk from closing all the way. go figure. i don't use them on mine.

 

nineball, Thank you