Welcome to mercedesshop
The brake pulsing, I would say is caused by warped rotors. Have you checked the rotors? The 115/114 rotors are cheap (I got them for $28 for the pair)
As for the idle dropping and then causes a stall. Maybe you need to increase the idle a little? I'm sorry not very familiar with gas engines...
Try posting this again in the Vintage forum! You might get more help there!
2008 BMW 335i Coupe