The noise your hearing is likely coming from the intake side. Pull off the 2 intake boots and replace them, they need to be done whether thats the problem or not. Check the DISA valve (black rectangle box in the intake manifold above the throttle body) and make sure it's snug and doesn't more around where it goes into the intake mani.
As far as your rough idle and idle surging issue, replace the Vanos seals and go from there. It might not be your only problem but like the intake boots, they need to be done either way.
1995 325i 5mt ArcticGrey/Dove - SOLD
2004 330ci ZHP 6MT SilberGrau/Black - SOLD
2001 330i M-Sport 5MT StaulGrau/Grey - SOLD
1992 Accord LX Sedan 275k miles all original - DAILY
2002 Chevy Suburban LT Autoride - TOY HAULER
2005 GMC Sierra 2500HD SLT - RACE TRUCK!