2000 e320 wagon auto, 145,000 miles, in Florida, use AC a LOT
Not sure what's relevant, so I'll mention all issues...

Annoying, but not critical:
For a couple of years now the AC will randomly start to blow hot air. I assume the coils are freezing and need to thaw?

Causing concern:
For a few weeks now, after driving for a while, when going slow (20-35mph) the car will feel like it's sort of skipping, it won't take the acceleration smoothly. I lift off the accelerator and gently try again and it eventually accelerates. It's like there's a hiccup at lower speeds (fuel? transmission? accelerator?). No codes are showing up about this.

ALARMING:
Two times, when the car has been driving for a while, going about 40mph and slowing down for a school zone and the car DIES!! All of the electronics/dashboard lights come on and then everything turns off - goes dead.

First time, I drifted over to the side of road and put the car in park. I tried a few buttons, nothing worked. Tried the flashers, they worked. Kept them on, took key out, about to get out of car but put key back in and turned it and everything came back on again. I drove for a few weeks with no repeat of problem. Called my MB mechanic, said not sure, could be the key is going bad.

Second time, same scenario, only instead of going full dead, it died for about 3 seconds and then everything suddenly came back on again and operated as normal. Drove straight to MB mechanic and he found no codes so couldn't diagnose. (key? throttle? transmission? fuel? electrical?)

Mechanic does service A and B as scheduled. Replaced battery about 4 months ago. There are always lights burning out on this car, which mechanic replaces at services.

Thanks for any help...