I was hoping to avoid posting in this thread, but just a couple quick notes:
Cracked heads in model year 2000 986s seem to be more common than any other year. I do have an engine with a cracked head and a water pump impeller that broke down and deposited small pieces throughout the engine. A small piece of impeller blocking a coolant passage in the head makes a hot spot and cracks. You can have a crack without intermix.
http://986forum.com/forums/229328-post4.html
https://www.renntech.org/topic/47374-the-dreaded-oil-in-the-coolant/
https://www.callasrennsport.com/Blog/the-porsche-m96-engine-and-cracked-cylinder-heads
Not saying that this is a case of a cracked head, just adding to the discussion.
I'd be interested to see what a pressure test of the cooling system shows.
The best way to test an AOS is with a manometer checking the vacuum at the oil filler cap. Try a search like this:
site:986forum.com manometer jfp aos in your favorite search engine and pick through a few threads.
If oil is getting into your intake from the AOS it is traveling through the tube that goes directly from the AOS to the intake (Duh). Check that tube for oil. Clean it. Run the car. Check that tube for oil. Is there significant oil in it again? It came from the AOS which is bad.
It can take a very long time to burn oil out of the exhaust system. These cars can put out a good puff of smoke on start up even with a healthy engine due to the flat design. If you really want to impress your neighbors and check if the smoke is just burning off residual oil, remove the exhaust and run it on open headers for a few minutes.
Good luck with it and let us know how things progress.
