My 2001 E320 4matic wagon started "bogging down" when I put the pedal to the metal. I could manually shift it but,when I put it back in Automatic it would barely move. I consulted MBWorld and found a number of posts with similar sounding problems. One suggestion was to reset the EC. I followed directions (twice) but no help. I was 180 miles from home and had to have it towed. Thank goodness for Premium AAA as it was no charge.
After arriving at my indy mechanic, the codes were checked and it was the "throttle sensor" AKA "accelerator sensor". Total fix cost about 300.00 and now she runs great.