2000 Dodge Caravan I changed the battery and YIKES!

Electrical problem
2000 Dodge Caravan V6 Front Wheel Drive Automatic 90000 miles

Hi, and thanks for answering these questions!

My Grand Caravan's battery died, so I bought a new one and installed it. I forgot to keep power to the system while changing the battery - I just unplugged the old one and plugged in the new one.

Now when I drive it, it shifts erratically and randomly - especially when reaching higher speeds. Every 30 seconds or so. Sometimes it will just shift out of gear and if I have my foot on the gas, the RPMs go through the roof. Other times, it just dies while still in drive - even on the freeway. :(

No code comes up on my code reader, but I have seen the check engine light flash sometimes while it is acting up. I tried hooking up my code reader to see if it would grab a code while driving - no luck - no code.

The tow truck driver said that these vans have to re-learn stuff after jumping them or changing the battery. How do I get my van out of pre-school?

Please help!
Thanks!