Electrical Problem... I'm pretty sure.

[t_rempel]

Hey guys, a little help here would be great, I searched around but didn't find much. If I missed something, please point me in the right direction!

Background:
Car is basically all stock minus brakes, alarm, and stereo. ka24e is all stock.
2 years ago put in a new battery and fuel pump. 2-3 weeks ago, I replaced my alternator. Until today, no electrical issues have come up that have troubled me.

Problem:
Remotely started my car after work like I usually do and everything was fine. However, when I got to the first stop sign (200 yards away), my car died and wouldn't crank. Textbook dead battery symptom.
I had jumper cables in my car, got a jump and everything was fine again.
I drove a couple kilometers and tried my A/C. It worked fine until I stopped at a crosswak to let a couple kids cross the street.
I tried to drive away, but my car suddenly had zero power, so I turned the A/C and fan completely off. My car drove normally again.
As I continued driving, I cranked my fan up with the A/C off and the car again lost power. It felt similar to when my fuel pump died, as though I was pushing through water.
With the car sitting in neutral, I'd rev it to 3500 or 4000, turn the fan up all the way and my rpm would immediately drop to 500 with quick bursts to 900-1000rpm.
Having no clue what the problem could be, I shut the car off, and tried to start it again. Nothing. Accessories worked, but engine wouldnt crank.
Now my car is sitting in front of the house.

[Pacman]

Grounding issue? I'd go back through the alternator replacement and make sure it is all good.

[t_rempel]

The negative battery terminal was much more corroded than I first noticed, so I replaced it and recharged the battery. Might be a little soon to say, but it looks like that fixed it.