Probable Cause:
1. Loose Bolt Or Nut Holding Pulley Or Damper
Tighten bolt or nut.
2. Pulley Or Damper Has A Defect
Install a new pulley or damper.
3. Engine Supports Are Loose, Worn, Or Have A Defect
Tighten all mounting bolts. Install new components if necessary.
4. Misfiring Or Running Rough