2007 Mercury Grand Marquis. Battery good, has been tested. Without warning, the car will act as if the battery is dead, clicking on start up. Requires a strong jump, doesn't fire right up. Once running, will start the next try. ABS and seatbelt lights have flashed or stayed on during these periods. Dash did not work once. has occured 3 times, required jumping twice. Both times jump was required, the car ran fine just before and after the problem occurred. Have cleaned battery terminals, no corrosion.