My wife has a 1999 polo 1.9 non turbo diesel 110k nice condition ,drives,starts and goes well but below 1300 rpm vibrates and you can feel drumming coming thro the whole body shell.So far I have:-

1. loosened off all engine mounts run engine briefly and retightened
2. Replaced 2 main engine mounts and checked rear tie mount.
3. checked compression on all cylinders
4. changed air and fuel filters
5. checked valve timing and pullies.
6. loosened in turn each injector fuel line while engine is running to see if all 4 have equal effect.

No joy at all , any ideas please .( I know these engines are a bit unrefined and am not confusing the problem with the normal vibes and clatter, I have driven others to compare)