I had a similar problem with my 97 E420. Car ran great, but at a stoplight the idle would kind of suddenly increase, then stumble and the motor would die. Would always start right up, but very annoying.

Bought an inexpensive code reader (Harbor Freight Tools) and found code P0100 indicating Mass Air Sensor. Ordered it from ******** AZ, ($268) installed it, and problem solved. Car idles steady, just like it should. Actually runs better too.

Kind of tricky to install, because it's mounted on the intake manifold down between the runners, and is hard to get at, just need to take your time.

Thanks, forum members.