Is it the end of my AT?

[Treppiede]

Good Afternoon Fellow SVXers,
I have a simple question for you. This past week the AT on my SVX has started doing something very weird, and since I never understood how AT trannies work I have no clue on the extent of the damage:

The car starts fine and I can shift into Drive/Reverse no problem.
I can drive the car at low speed no problem, it appears that the car switches to 2nd gear as well, it's hard to understand but it seems like the problem is in 3rd gear. Basically anytime I find myself driving over 30/40mph, the rpm needle just revs from about 2500rpm all the way to about 4k (without pulling) and starts pulling again only past 4k. In other words I find myself cruising at 40-50mph at a high rpm, it's like if it doesn't want to switch to 3rd (or 4th?) gear. I wouldn't say that she's slipping because past 4k rpm she pulls hard all the way to redline, seems like I am in PowerMode although the green LED doesn't light up.

What do you think this could be? If it's a simple fix I would love to fix it so that I may drive it a little longer before my 5mt swap, however if it's more complex I guess I'll either have to do the swap now or sell the car because I don't feel like wasting any amount of money on an AT which I hate to begin with.

I've been carefully driving her around trying to keep the rpms under control, but now of course she's doing something like 5mpg due to the high rpm issue. The tranny fluid is fairly new.

Any advice?

Thank you in advance!

-Walter