So, you ran on the same trans fluid for 90k, then changed it. Tranny started slipping right away? After a few thousand miles? You changed with the factory-recommended fluid?
I have been running my Jeep on the same fluid since I bought it (60k miles since then). Don't know long it went without a fluid change before I bought it. It had 140k when I bought it. I want very much to change the fluid, but now I'm nervous...