OK, after letting the engine idle for 30 minutes, the rattling almost goes away completely. Every minute or so I can still hear a faint rattle for a few seconds and then it will stop again. I hope this helps.

Reading his comment above, I'm wondering if it's the AC compressor cycling?

__________________
Richard Wooldridge
'01 ML320
'82 300D 4.3L V6/T700R4 conversion
'82 380SL, '86 560SL engine/trans. installed
'79 450SL, digital servo update
'75 280C