Based on the symptoms you're reporting, a worn timing set could be a contributor. A new chain will likely help.

DSG offers a gear drive for both the DB2 & DS4 equipped engines. If you have a 1982-1993 engine, you can use their standard "Dual Idler Gear Drive", which is about $100 less expensive than their "Phaser" gear drive, which includes a reluctor wheel for the crankshaft (that's why the increase in price).

If you have an engine newer than 1994, you'll need the Phaser even if you are running a DB2. Or, you could machine a spacer to make up the difference for the thickness of the reluctor wheel. Or, install a damper made for a 1982-1993 engine.

Jim