I am noticing a knocking sound coming from my 2.5i 2007 Liberty

It is more prevalent on the left hand front passenger side of the car, down towards the door/floor
It is in time with the engine at idle and most noticeable, but as I accelerate (no load) the noise disappears.
I can't locate the noise outside of the cabin under the engine bay, but it is audible inside the cabin at a low rpm (idle)
Of the brief research I've had a look at, seems to be pointing to the Fuel Line Damper.
Although I can't find anything to specific on Legacy/Liberty models,
Would I be correct in saying the Liberty has only one damper, near the battery? Would this be for the feed or the return?
Are these known to fail and cause a knocking type noise?
If anyone has any further information/experience on this it would be great.
I have attached an example of the part I am talking about (not my Liberty)
Cheers
