Trans Possibly Acting Up

Hey guys, my Galant's giving me issues today. I just started delivering pizza in it again a few days ago, and this morning when I left the house to go to church it was acting funny.
It's over-revving between gears like the fluid's low, but it isn't. When it shifts between gears it will rev freely, until I let off of the gas and it decides to shift into the next gear.
BUT HALF THE TIME when I pull off from a stop it shifts fine, although quite short. 1500RPM-ish when 2500RPM is more common.
But either way, when I drive and give it heavy throttle it bogs down like it isn't getting fuel. Idling fine.

It was running fine yesterday, I drove 180 miles and everything was great. Getting about 19mpg driving a little aggressively, but everything was smooth and happy. Now today it's doing this. Car has 196k and has recently had a major trans cooler leak fixed, but has fresh and clean Diamond 3 ATF in it.
It is throwing codes for O2 sensors, misfires, and the TPS, but I'm not confident that the TPS would cause it to rev like that between gears.
Am I looking at a Torque Converter, or is it tranny time?
I've done some googling, and not come up with anything solid.

At 196k on the v6, the trans is probably on it's last leg anyways. Just search for my trans issue with the keywords shifter solenoid and you'll see why I'm saying that, it's a known issue on our cars. I'd fix the problems that are sure first however: tps, o2, plugs most likely. My approach is start with the easy and inexpensive stuff first to narrow it down, before you write off something big like the transmission. Otherwise good time to start collecting 5sp parts.

I've got a message out to a guy on Craigslist about a 5spd swap, but I was hoping to be able to put it off until my Volvo was done. If I can find a good sportshift auto out of an Eclipse (V6 Galants aren't as common as V6 Eclipses around here) can I use the sportshift or does it have to be the Galant auto?
I'm trying to work on the car today or tomorrow. Changing o2 sensors, plugs, wires, cap, rotor, and TPS.

I don't think it would be that difficult, you might need the tcm to go with it but I'm not sure. A part no crossreference would verify that.

I have a full AT out of my previous Galant. It's a 2002 however, depending on the build date of your car it might be compatible, but if not it can be a headache. I do have all related parts tho, and I'm about 4hrs away from you.

I changed everything today and it ran fine for one good 0-70 pull, then the check engine light came on and the code is back. All other codes are gone.

Im throwing a code p1603, battery backup line. Everything I've read points to the ECU. Changed several throttle sensors and the code comes back. Out of ideas.