Originally Posted by MOS95B
I definitely agree with getting it hooked up and scanned, but one other thing to think about. What kind of shape is your battery in? I had a Corsica that acted a lot like what you're describing (including eating money), put a fresh battery in it and it ran like a champ.
Replacing the battery would have wiped the Keep-Alive Memory due to the 15 minutes or so that the car was without power, so re-learning the operating parameters afterwards probably helped your Corsica to get its head on straight again.
In the case of this Bonne, though, good grief: The absolute first thing should always be to see what error codes are stored by the SES light, assuming that you have an SES light going in the first place, and practically everything other than sunspots or Rising Tensions in the Middle East will turn on a Check Engine light these days.