I have a 2003 Ford Taurus, it had been slow starting so I took the battery in and I was informed that it was bad. 3 days after I replaced the battery, the car has been slow starting again. I had the starter replaced 2 1/2 years ago
The first thing you should do is have the alternator tested. It sounds like your cars alternator might not be charging. If this is the case it would explain why your car is dead just 3 days after replacing the battery. You can get it tested at almost any auto parts store. Be sure to have them "load test" it.