Weird 'thrumming' noise from airbox. 1.6 diesel

[Exjag]

Just wondering if anyone else has a 1.6 diesel and noticed this noise? It might be a ' diesel thing' but this is the first one I've owned.
If I put my ear by the airbox, there is a definite 'thrumming' or drumming noise. Taking the trunking off, it is louder so is definitely from the airbox.
It's not that the filter is loose, it's firm.

Thing is, I always feel a slight 'bobbling' sensation when driving, like the engine is slightly misfiring ( but it's a diesel) and I'm thinking the rhythmic 'thrumming' and the 'bobbling' sensation are linked?

If any of you kind people could have a listen to their engine/airbox and let me know what you hear I would be grateful.

[andy2019]

cannot help you out with the sound your getting from air filter area. but the slight misfiring may be sorted by useing a bottle of injector cleaner in fuel tank every few months, and get the fuel filter replaced every 2yrs or once a yr if you do loads of miles..

[Exjag]

Hi, I've been using Millers snake oil for the last 3 months and no improvement. I don't do loads of miles, but I doubt the fuel filter has been changed, so a good shout there.
My concern was the likelyhood of a sticky intake valve or worn cam lobe causing the noise and the 'missfire'.