I might have fried my sensor.
 

I was playing around with my MS last night in the garage, and when the wife got home she distracted me with "activities" resulting in me forgetting to switch the car off. I woke up this morning and saw the MTX-L lit up and realized what I had done.

This morning on the way to work, my AFR readings were wonky, jumping around wildly on occasion, and the car stumbled a few times. Can a wideband sensor be damaged from being powered for a long time with no exhaust flow?

I don't have an answer for you, but I too am interested to hear what others have to say on the subject. In the past I had noticed that if I would leave the car in the key-on-engine-off position for 5 or 10 minutes before starting the car, I would sometimes get some strange behavior from the LC1. However, I haven't noticed the same problems reoccurring any time recently (for the past year, since I replaced the sensor).

The wideband probably recalibrated itself when the voltage fell too low. Perform a free air calibration.

Well, I found the issue. Taking your advice, I did a free air calibration and it didn't help. Stumbling actually got worse, so I started at the beginning. Measured the coil pack resistance, it was fine. Spark plugs looked good. Measured the spark plug wire resistance, and the #4 plug wire was completely fried. :confused:I doubt the issue was related to me leaving the car energized, as all 3 other wires checked out fine, but you never know.

Anyway, problem fixed. No more stumble.