Not strictly Toyota but looking for some advice. My girlfriend has a Mazda 121 bubble 1.3l that is having some trouble. It started out stuttering and not idling correctly and got worse until it would drop out unless accelerating. We pulled a code for an air flow sensor which we replaced and the code went away but the problem persisted and continued getting worse until now the car won't start. Speaking to an auto electrician he thinks it is likely the ecu but he was pretty vague. I noticed that there is only a few ohms resistance between the + and - leads with the battery disconnected and keys out and the battery is now dead also. Any one have any suggestions?

Alternator? Have you put a different fully charged battery in?

I did try my Ke's battery in it, but when I put the leads on it sparked and I was worried it was shorting the battery so I didn't get to turn the key.

Id try a new fully charged battery. Sounds like your alternator was slowly dying.