[husker boxster]

There was an old Wheeler Dealers episode (so old that Edd was the mechanic and they were in England) where Mike bought a 986 w/ Tip. The issue was either the Tip wouldn't shift automatically but would manually or vice versa. The fix was to change the trans fluid. Might want to track down the episode on YouTube and see if it matches your issues. Sorry I don't remember the exact specifics of the show, but it was 12+ yrs ago.

Good luck and welcome.