I replaced the spark plugs and wires, and it seemed to really help the acceleration and hesitation problems. (WOW, this thing is fast!) But it still has a rough idle, and is making a ticking sound, almost like it has an exhaust leak. The sound goes away at higher RPMs and the engine revs very responsively and smoothly. I am thinking this is probably a fuel issue.

My local MB indy shop said that one or two cylinders aren't firing properly (duh). I'm going to drop it off there tomorrow morning and they are going to diagnose it. Hopefully I can get some answers that way. He said they would do a compression test, then check the fuel system.

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Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles