Hi, I apologize for resurrecting such an old thread but it matches my symptoms precisely. The only difference is that I don't always go into limp mode, in fact its only done that once. I pull over and turn off the ignition and restart and it runs fine until the next time.
btw, making an appointment with my indie to read the codes, so I don't know if my problem matches precisely..

I originally suspected a weak battery but I've recently replaced it and then it happened again! So what was the final resolution to your problem, last post reads MB tech is looking at your issue?

__________________
Ed "Don't Benz's just feel better..."

Current wives...
2000 ML430 Skyview "The Mel"
2000 CLK430 Cab "The Cab"
85 300D Turbo "The Diesel"

Past wives...
92 300E
85 190E

"One should as a rule respect public opinion in so far as is necessary to
avoid starvation and to keep out of prison, but anything that goes beyond
this is voluntary submission to an unnecessary tyranny, and is likely to
interfere with happiness in all kinds of ways."
Bertrand Russell