Ok, the computer in my dash has finally failed me... The screen died in this cold weather, and I need to get an error out of my ECM.

I dont know how to provoke the ecm into diagnostic mode to flash out the errors for me. After I hit the snow drift, I get a check engine light when I am NOT on the throttle. As soon as I start to accelerate, it goes out. I can smell my gas (and $$$) burning very quickly, as closed loop mode sucks a lot of fuel!

You could buy or borrow a scan tool, or I know that on some vehicles it is possible to use a paperclip or jump wire and jump two specific contacts on the diagnostic plug, then turn the key on and the SES light will flash a number of times, telling you what code(s) have been set. Just make sure you find out which ones to jump so you don't short anything out. If you have a service manual it would probably say in there, or someone else on here might know for sure.

Ok, I found out the procedure, and have come up with a "CODE 22", which means "open throttle position sensor circuit".

I replaced the TPS last year, so I think maybe its just out of adjustment...

it's possible that the carbon resistance track in the TPS got damaged in a hard stop (hitting a snowbank).
and your first post is incorrect as closed loop is when the ECM/PCM is cycling normally to improve mileage it is Open loop that it goes into when a sensor/something fails and the 'puter is using it's built in fuel/spark maps, open loop is at cold startup/or when the o2 sensor cools below 500-700 degree's and quits cycling rich/lean/ and it also goes into open loop at WOT.
closed loop-better fuel economy/emmisions/drivability
open loop- worse fuel econ/built in spark/fuel maps
hope this helps
schlim