I had a 2001 986 as well with the same issue and ran thru all those fixes as well. Have you REPLACED the MAF?? Just an idea.
Here is the 986 DIY playlist of videos I did on my car's issues.
https://www.youtube.com/playlist?list=PLbBMHPz04qDW2lbqUZ4p2yWK9joftSOEO
Brian
HTTP://986Brotherhood.com