Comp test
Drop the oil, filter it and chop the filter in half to look for swarf
Remove aux belt and check for play in any pulley
Check viscous fan clutch
Crank pully
Ensure all coil packs are tight
Whip off the cam covers to make sure no visible damage
Ensure nothing exhaust wise has cone loose, heated exhausts with loose brackets etc can cause vibration back through the whole system
Can you feel it through the gear stick?
Does it go away clutch in? (Unsure if auto or manual sorry)
All fluids topped up?
All things I'd check,
Edit: sorry just read the whole thread n realise you've probably checked a lot of these things
Best of luck