what would cause loss of power except for the headlights?

that's an extremely vague question. I'm guessing it runs and loses power? But isn't a battery issue? I just got done diagnosing a bad ground issue with my 91 festiva. It took me months, but I had other transportation or it would have been a lot quicker, to figure out I had a bad ground on the passenger strut tower. Looked normal and clean. I took it off, cleaned the area and connector and put some anti-seize on the bolt and snugged it up and viola! my issues were: I could bump start the car but it wouldn't start, crank, turnover or anything. Just one solid CLICK. It was sluggish going up hills because the engine needs that solid ground. Sometimes my fuel would cutout. All of this and more because of that one little ground wire. I'm going to be adding more soon! let me know what you find out or if it is a totally different issue. Your spark plugs, disty, starter, injectors and other stuff rely on the grounds to work properly. You can try hooking a battery jump neg to battery neg and other neg to engine ground by the disty and see if it works right. If it does good, then remove the ground and see what it does.