so my transmission doesn't want to shift anymore. i jumped on the freeway this morning and put it in overdrive and it was fine for about 8 seconds, then i realized it wasn't down shifting. i had to get off the freeway because i could only do 20 while in drive or OD and i had it red lined just to keep the speed that high. i checked the fluid and it was way low. i added a quart and a half hoping it would fix it, but nothing. still messed up. i crawled under the truck and theres fluid on my vent line and its been slowly dripping from there the last week or so. Ive been digging through my manual to try and diagnose this. so far Ive come up with governor or a band. any help is greatly appreciated. PS, i hate transmission problems......

 

I had fluid leaking from my vent line and (they said) that some internal parts of the torque converter broke and went through the transmission and blocked it off somewhere, so when it would try to pump fluid, it would just eject it instead of overpressurizing and breaking something.

Ended up having to get a rebuild.