So, since I last replied I have replaced the battery cable terminals and cleaned the MAF sensor. [I'm replacing the air filter today, as well. With the MAF that grimy, it's apparent that it needs a new filter.]
Unfortunately I'm still getting the rough idle, but what is really concerning me is now, whenever the RPMs drop (particularly on deceleration and idling), the engine stalls out completely.
Just a brief rundown of the sequence of events from start-up to stall-out:
1. Turn the ignition and engine starts with no problem; engine idles (in park) at around 1000RPM
2. Shift into drive or reverse and the RPMs drop to ~600-750RPM range.
3. Drive, accelerate: Generally, no problem.
4. Decelerate, come to a stop: RPMs drop to ~500 before completely stalling.
I've noticed that if, as I'm coming to the stop and the RPMs hit ~500, I give it just a little gas to bump up the RPMs, I can prevent it from stalling. After that, it typically idles with no problem in the ~600-750RPM range.
Even without stalling, the engine shakes and shudders pretty roughly during idle. It gets to the point that it feels like the entire car is shivering.
The odd thing is that the CEL is off and has remained off. I can understand the CEL being off after the ECU reset that comes w/ prolonged battery disconnect, but it has remained off for days now. I'd expect whatever is causing the erratic idle to have triggered the CEL by now.