I've noticed a slight rattling from the engine bay of my 2000 when the engine drops in revs from startup. I'm assuming the rattling starts when the engine begins to vibrate more at lower idle speeds. I haven't been able to get it on a lift for inspection but was wondering if anyone had a similar issue. I'm wondering if it might be the A/C compressor clutch housing? The A/C works fine but the rattling does not go away when A/C is turned on.