My daughter in law has a 1996 es320, on Friday 8/22/08 she went to work and everything was fine. When she went to go home that evening, she started the car and it ran for a minute then died. The check battery indicator came on. My son went to help her and replaced the battery in the car. The car made it half way home then died. We towed the car home and I brought the alt. to my rebuild guy, he said it was bad so we replaced it. All is charging well, but the car has developed a loping idle. There is a vacume hose on the laft side on the engine in a black plenum that when removed the problem seems less intense. However, the problem seems to be there weather the mas is installed or taken out completly. I am an old school chevy guy but it seems my life is going to teach me about these MB's. LOL I had checked for vacume leaks but could not find any. There was also a check engine light on awhile back and my son took it to a frind to get the code, seems it came back egr problem, they reset the codes and the light stayed off. Any ides and info would be greatly appriciated as my son, who is just out of the service, and his wife are just starting out and funds are low.
Thanks,
Karl

Have you driven it any. When the alternator was out all the adaptations were reset. It may change if you drive it some. Otherwise look to air leaks and sigle cylinder misfires due to plug connectors.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Thanks, I'll check out driving it some 1st since that might be easiest. also when I said the check engine light was on and codes checked then reset, my daughter in law told me the light came back on about a month later, guess I have to get an obd2 scanner huh?
Karl

Assuming the car is either a Mercedes E320 or an S320, and not a Lexus ES, you may have a clogged EGR pipe causing the EGR fault and CE light.

Will single cylinder misfires cause a surging idle?
Karl