That's strange... my 07 328 w/ 65k KM just had it's eccentric shaft sensor replaced Friday... it was fouled/soaked with oil says the repair log. They found that while doing the n52 valve tick fix (see post 9 in this thread)
Car seems to be much, much smoother now. I'd had similar issues w/ a really low/rough idle at lights but no screeching.
2007 328i E90 6MT. Sport package, premium audio... so far.