I'd do two tests first.
I'd check your fuel pressure at the fuel rail anticipating the possibility that it's the early stages of a fuel siphon o ring issue and review Andrew Wynn's write up on that.
I'd make a low cost smoke tester and do a smoke test. I found vacuum leaks in three locations that caused similar or identical symptoms to what you are experiencing. One was the Disa O ring, the second was a cracked little plastic fitting in the hose going to the dipstick tube and the third was a vacuum leak after reinstalling the rubber elbow on the Idle Control Valve improperly in 10 degree winter weather..
Additionally I'd check the CCV system for old age and potential clogs.

__________________
2001 x5 3.0 (sold with broken motor), 1990 e30 M3, 1991 318is, 2002 325i, 2008 335i Dinan stage 3 6 speed,