ETC is "electronic throttle control". If you had a decent scan tool you should be able to see both commanded and real throttle openings. I have an OBDLink MX which works with my laptop and would help a lot in a diagnosis like this one.

In the meantime, disconnect the battery for 30 minutes or so and reconnect. Sometimes these modules just get angry.

A bad IAT sensor would make it run quite rich, but again the scan tool would tell you what it's reading.