i got a 91' deville and if i leave it for a few days the battery will be to low to start the car the battery is new and good my alternator also works so i not sure what could be wrong the lights in the car doesnt stay on. :bonkers:

Either the battery is no good or there's something staying turned on inside the car that's making it do that. There are a lot of posts around here about that kind of problem that will tell you some ideas for how to fix it.