Where to start?

I experienced symptoms similar to yours about 4 months ago. Unfortunately, the rough idling for me was due to a faulty #6 fuel injector and a leaking head gasket near the #1 cylinder. Both replaced. Additionally, I had quite a bit of surging at idle. The vehicle would consistently surge between 500-800 rpms. This lead to the diagnosis of the faulty IP.

Questions:
1. Does the rough idle calm down as the engine temp rises?
2. Is the car "hammering" consistently?

__________________
Chris

'04 ML500 - 53k, Inspiration Edition, Desert Silver
'11 Audi A4 Avant - Brilliant Black
'87 300SDL sold
'99 C280 Sport sold
'85 190E 2.3 sold