So the other day I installed new fog light on my car and the battery was disconnected for about an hour or so, probably longer.
Before the fog lights, when I started my car up in the cold it would rev between 1.3k and about 1.7k and it would start right away too.
The day after I put the fog lights on, I started it in the cold and it rev's around around 1k - 1.1k, and it has a weak, dreaded start.
After I got out of my co-op job today, I started her up and she started fast, but was revving around 1.1k so to warm the engine up more, I pushed the gas for a few seconds. Once I let go, the rpm's started dropping and the engine stalled. I started her back up, she went to 1.1k then started driving before the engine stalled again. Didn't stall on my way home.

Basically, I'm not sure what the problem is, but since the ECU got reset, would this have effected my A/F ratio and made my engine stall or would it be something else that is causing the problem?

yeah the ECU needs to learn the idle again

Pull off the negative battery terminal or the ECU-B fuse in the engine bay for a few min and after you reconnect either one, start the car and let it sit for about 10 min. Mine took about 5 min to get to the point where it didnt sound like it was going to throw a rod after i did it this week. The lackluster idle is expected until you let it sit before driving after you reset the ECU.

ECU-B or EFI fuse? i'm not sure which one it is so I do both.

all you need to pull is the EFI fuse for ~10-15 seconds, according to the BGB.