I have a 97' A4, and all of a sudden my reverse will just go out. Perfect example:
I drive around shopping all day and reversing out of parking spaces. Get done with all that and go to my dad's to pick up something. When I get ready to leave, NO Reverse..Just like that. I had no problems through the day that would show any signs of Tranny problems, no gear slipping, hard shifts, high revving or anything.
SO I drive around for about 3000 miles and all of a sudden, Reverse works again. Just as simple as leaving one place and it not working to going to another and it working then. It has done this twice (and yes it's working now), so when I asked someone about it they suggested a "multi-funtion switch for the transmission". I bought it, put it on and it didnt fix it. Could there be a short somewhere? Anyone else with this problem? I did have it hooked to a machine that pulled up the switch code.

 

What kinda places are you going to that they're 3000 miles apart? Hopefully not just running errands. And also, it would be pretty amazing if you could put 3000 miles on the car without using reverse.

My old car was auto and used to do something similar. From reading I'm assuming it's a TIP, my car would go into reverse then when i would stop and try to put it into drive it wouldn't go into gear. I would either put in in park and wait like 30 seconds or put it in park and shut it off and start it again and it worked fine. I know this doesn't fix your problem but maybe you could that next time it goes out and you need it. Good Luck.

 

I mean just general driving around! I do a lot of that. I have taken her to KY, FL, NC (twice), and AL every weekend (for the past 2 months).