Check your fluid, if it's fine, then this a death knell. Hopefully, your fluid is the issue, but mine did this and the fluid level was correct. Next thing I know, dead a604. Good luck.
GAH this is happening to me....its only a matter of time and i know it. no one believes me they all tell me the tranny is fine...wtf man i was in school to be a mechanic and granted i dont know everything but i know damn enough.
oh well still dont have the money to fix it

The sign of imminent death for me was when it would just stop working and drop out of gear whil going down the road. Then I would wait awhile and it would work again. If your problems are anything like mine were, REPLACE THE TCU NOW, and it may save you some trouble. I guess there are some capacitors in there that "get tired" with age and swell out and leak, causing issues. When mine physically broke was when I coaxed it into limp and didn't get off the interstate in time before the spindle blew up.... Again, good luck man....