The car is a 230Kompressor.
I think that the main problem has been trying to deal with the worst dealership I've ever heard of -- Cardenas Motors in Harlingen, TX. They suck!
Thanks for the good advice. I think I'll ask another dealer (Austin probably) to check the car out. Since it's still under warranty, they really shouldn't have a problem doing this, right?
I was noticing on alldata.com that there are two TSBs that refer to the problems the car is having (brakes and stalling). The dates on the TSBs are 9/99 and 12/99. If the car was built before that (it's a 2000), then perhaps the TSBs can address what's wrong -- assuming the dealership knows what it's doing.
I think I'm most surprised at how unhelpful and unresponsive Mercedes Benz USA has been. When dealing with Audi for my A4, they have been great. I know other people have complained about Audi service, but I'm thrilled at how I've been treated by my dealer and Audi USA. First rate.
Anyway, thanks for the good advice.