I have a 2006 Toyota Sienna with 207,915 miles. My 
transmission has some problems. At first when I stopped I pressed the gas and the vehicle didn't move, the engine did rev. I had to put it in Park and it moved again and I had to do this a couple if times to get to a parking lot and safety. After many hours, I was able to drive it again, but as the bright l vehicle warmed up it started the same problem. It would buck when hurting the second and third great but drive great after that. This time though when I put it in Park it didn't work, only in reverse. I had to shut the vehicle off then on and it would go. The take off was very slow, and still would buck going to second gear and going to third but not as bad as going into second. Before it switched to second gear it would rev really high. I changed the two input/output sensors and nothing. Someone mentioned the solenoid. What's is your take? Or should I get a new transmission? And yes, I learned try to late to not flush the transmission about over a year ago, why I don't trust many chain mechanic shops.
A
Sounds like it needs a full replacement. I think you would be throwing away your money trying other fixes. And I hate telling people that, but going by the troubles your having it sounds severe and is pretty symptomatic of a transmission that has gone out.
If you like the van, you can get a remanufactured one. I would not recommend rebuilding what you have. The other option would be to move on to another vehicle.
Odds are it needs new transmission when it's gone that far most guys aren't very good at rebuilding those Toyotas you better to get a remanufactured one
Any codes? Also don't trust chain mechanic shops your right. I'd recommend finding a trustable mechanic, you can find a list of user submitted good mechanics in the FAQ page for said topic.
Unfortunately for you thats the most common problem (issue with the transmission loosing power when slowing down or at a stop) and often requires a new transmission, which would cost $$$$.
