We have a 2003 Diamante that has an engine rattle. We took it to a mechanic who told us it was the TB tensioner pulley that was making the noise. We replaced that, the idler pulley, the timing belt, the adjuster and the water pump. It still makes that noise. It's really loud when you start the car, but slightly quiets when you drive. The car drives great other than that noise. What could it be?

Thank you for your help!