Re: trouble running when cold
The ELD code is most likely from the O2 sensor heater. I'd bet something in the O2 sensor is shorting because it's (obviously) broken.
Well, the first thing I'd do is disconnect the old one, just for safety so there won't be any possibility of damaging the ECU. It's broken, so it doesn't matter if it's actually plugged in or not.
Do that before turning the car again.