just a couple days ago i was driving about 45 in Overdrive when there was a thud and it poppped out of gear and started free revving. Now if i come to a complete stop and try to accelerate in Overdrive it will just rev up.
To remedy this Ive started to used Drive exclusively, then when i get up to highway speeds i can push the shifter up into overdrive, and as long as i dont hit the throttle i can just coast in overdrive.
then when i slow down and try to restart from a stop i have to put the trans back in Drive again.
Question is: how long can i expect to keep going like this?
Not real long I'd say. Sounds like there is either a damaged or stuck valve in the valve body or some burnt up parts. The A4LD is not known for strenth or reliability so I would take it to a transmission shop and have some work done. If you do decide to take it to a shop, have them install a "shift correction" or "shift improver" kit and synthetic ATF. That should ensure good, reliable performance for years and years. But as for driving it in its current state, I would stay close to home and keep the trips short. I've never heard of an automatic lasting very long after it develops shift issues.