[Cyber10]

When my transmission died it did almost exactly the same as your except I was doing about 40 up a ramp to get onto the interstate. My car shifted up and down a few times before I heard a thud and I had no more power below 4 gear, fortunately I made it over the ramp and got up into 6th and didn't hit traffic on my way to work and was able to get it to a shop later that day.

I have no clue what exactly went wrong with mine as I chose not to rebuild it and bought a new one instead, tuner agreed that whatever the problem was it was definitely the transmission(as if it was even a question after seeing them pulling shards of metal out of my converter lol). Seems like the only difference between us is my low gears went while you're having problems with higher gears. Let us know what the dealer ends up saying, I'm genuinely curious as to what it is/what mine could have been.