Regarding vacuum lines, do some research over on Bimmerfest, in the E39 forum. Lots of good information there on the M54. I had to replace the vacuum line from the secondary air pump valve to the electric valve mounted on the back of the intake manifold, because when I replaced the valve cover gasket, I pinched the line that runs around the back of the engine. The rubber used in those vacuum lines doesn't last very long, and it'll eventually crumble and give you a nice leak you'll wish you didn't have.

Just my $.02 worth...

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2003 E53 3.0i
DOB 10/15/2002
Sienna red, Savannah Beige Dakota leather
Type FA53, Engine M54B30

2018 G02 30i
DOB 4/21/18
Black Sapphire Metallic / Canberra Beige Vermasca leather
Engine B46O