OK, for those of you not familiar, here is the original thread.

Stalling & Rough Idle Cured - But Why ???

The long and short of it is that I was experiencing an extremely rough idle and stumbling/stalling when accelerating in my 1991 300E with 135K miles. I reduced the spark plug gap on all 6 plugs from about .040 to about .030 and the problem went away. The car idled and ran as smooth as silk for a week! Then just today at lunch it did it again. It only happened 3 or 4 times over the hour or so that I sat in my car eating my lunch. It did that same abrupt misfire which previously only got worse.

Does this mean I need a new coil? I'm thinking the spark had trouble jumping the .040 gap, and changing it to .030 reduced the resistance enough for it to jump.

Any thoughts? If I leave it like this, it'll probably be doing the rough idle and stumbling/stalling within a couple of weeks...

What do you guys think?

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