I have experienced much the same problem with the dampener pulley on a E46 320d after we replaced it with a new pulley. This one though took about six months before it started causing vibrations. It was so bad that when one was in traffic at a stop sign or robot the car would make such a racket that it was embarrassing. I replaced it with a new one from Goldwagen and as it was just under a year old they gave me a new one. The brand was Corona (not certain if i have the name correct but it was not Topran) and problem solved. I had replaced the spring tensioner, other pulleys and was just about to replace the power steering pump when i found the problem to be the dampener pulley. I am 99,9% sure that it is your problem as well.