I've had similar problems, intermittent rough idle. Twice the dealer has determined, from codes, that my air mass sensor is bad.

I usually buy only Chevron, but once in a while I fill up at my carwash to get a discount on gas with a wash. I don't tell the dealer this, but I think I may have gotten a tank of less than 91 octane there. The rough idle sometimes comes after certain fillups. It certainly did the last time.

They reset the fuel adaptations and off I go. What I suspect is that the ML doesn't adapt correctly to the lower octane, on the other hand, it could be your air mass sensor. Have them look at that before you lapse on warranty.

__________________
Ed "Don't Benz's just feel better..."

Current wives...
2000 ML430 Skyview "The Mel"
2000 CLK430 Cab "The Cab"
85 300D Turbo "The Diesel"

Past wives...
92 300E
85 190E

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