I really doubt it's any of those since they are all nearly new, but you never know. I'll check and report back.

I threw a couple bottles of Heet in there and filled up. Overall, the car *seems* to idle more smoothly, but I still get the occasional jerk and the car will still die backing out of a parking space or the garage if it isn't warmed up for a few minutes first.

I'm beginning to think my whole theory of this being related to fuel system is not correct. The occurrence at time of fillup may have just been a coincidence. I will be doing a full inspection sometime in the next week; hopefully I'll find something obvious.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280