I checked the connection on the AMM, and it looked good, almost no oxidation. I picked off what I did see, then reconnected.

At idle, now floating somewhere around 1100-1200rpm on first startup, I tried disconnecting the AMM while the engine was running. The idle immediately dropped to a low, but steady 750-800rpm, with a slight hiccup from time to time. When I reconnected, the car instantly jumped back up to the 1200rpm range, then started inching closer towards 1500rpm. The idle's never been rock-solid anyway, but it was never this high, starting just about a week ago.

You mentioned that I should clean the other connections, as well. Which other connections do you speak of, and where are they located? I don't know where the O2 sensor is, but I can guarantee that it hasn't been changed since I've owned it, in 4 years and 60k miles (car currently has 187k miles on the clock). I have never cleaned the throttle body.

Major symptoms are high idle (above), touchiness to the throttle, bad gas mileage, and what feels like a fuel cut-off from time to time. Only the high idle was present before the check engine light came on, then the others started.

Thanks again for any input.