Sounds like a good list of culprits.

On the E39M5 we recommend prophylactic CPS sensor replacements and vanos cleaning and seals. Sensor is $75 and an hour. VANOS clean and seals is 2 hrs. THis is usually DIY as most big shops/deaelrs havent figured this out: they follow the 'test bad=replace vanos board' philosophy

With a GT1 or equivalent tester you should be able to run a vanos test to try and separate CPS fault from sluggish vanos....