So, it definitely drives even better than it did with an overall smoother feel, but I'm still idling a little high when the engine is cold, at about 1200 RPMs.
After I drove about a mile to the train station, I put it in park to wait for the train and the RPMs were floating between about 600-800 RPMs, but it felt a little shakey. It feels like they're holding steady around 800, then suddenly drop to 600 then climb back up to 800.
Other than this idling issue, the car seems to run just fine. The only other thing I'm concerned about is I think my thermostat is stuck open. The temp doesn't seem to get any higher than about 140 degrees. I'm constantly running pretty cold ever since I had the system flushed and a new t-stat installed.
I could also have an air bubble, because every once in a while, the low coolant light comes on. It never stays on for more than 2 minnutes at a time, but the coolant levels are full.

Is there anything else I should check besides MAF? I don't even know how big of an issue my idling is, because I've only stalled once and it was before I cleaned the MAF, right after I fixed a vacuum leak.
THAT's what I'm most confused about. Why would fixing a vacuum leak cause me to stall after starting the car? I changed a line that was completely cracked an disintegrated.

Thanks again!