ps2cho, worn voltage regulator brushes will cause all the warning lights to illuminate also since the alternator is not recharging the battery properly. Though not all alternators have a screw-on voltage regulator with brushes.

We have been struggling with the same ABS light with resulting intermittent bad idling/stalling on our '91 300 E for @ 3yrs untill it got so bad the car wouldn't start any longer.
In dry winter climates it never was a problem, but during rainy/humid summer mnths it would act up again... Well when it finally died I took it back to the specialist (who's very good BTW) where it is maintained according to schedule.
Turned out to be a BADLY BURNT DISTRIBUTOR CAP AND ROTOR!!!
Problem solved completely.
The car still has its original OVP.

It was interesting to note that the car only ran poorly for a few seconds to a minute at a time when the ABS light came on - low voltage - but when the light went out, performance returned to normal.

I didn't think it would be the OVP. I'm going to swap out my Dist Cap and Rotor because it is doing the hesitation thing and sometimes starts perfectly and other times takes a few cranks. And it seems like an electrical thing by the way it acts. Nice fix and hopefully wasn't too costly!

We did swop out OVP's at one stage - to no avail.

Did you notice it started any better when you did the swap out or did it just not stall?

It starts up faster now, idles stronger when cold, there was also an improvement in performance.
The ABS light would randmly come on while starting up first time in the morning. That's when idling was low and rough and motor wasn't pulling strong. When the light went out after a few secs to a minute, idling and performance returned to normal as if nothing was ever wrong. This got worse and the car became hard to start when ABS iluminated and the stalling also manifested itself. It got so bad that the ABS light wouldn't go out for quite a few kms, and the car wouldn't accelerate.