Mercedes Benz repair: 2004 E500 4Matic, flex hoses, vacuum pump

Question
I recently purchased a 2004 E 500 4Matic and I have a question about an issue with the brakes.

At slow speeds and when I pump the brake peddle a few times, I hear and feel a pump of some kind kick-in and it vibrates up through the brake peddle. I also hear what I think is the same pump stay on for a few seconds (10 or 20) after I turn the carr off. It also feels, I think, like the brakes grab a little bit, even when there is presure on the peddle.

I tool it to the dealer who replaced some parts pursuant to a recent "recall" notice, but this problem persists. Any insight on what might be causing this would helpful to me when discussing it with the dealer.

Thanks.

Answer
That is the ABS pump felt through the pedal.

The stopping issue sounds like bad calipers/flex hoses causing the ABS to activate.

The pump you hear running with car off should be the central locking vacuum pump = there is a problem with the system.