2000 Jaguar S-type. Selling as is

This is a 2000 Jaguar S-Type. It was an amazing car for years. It became my daughters car and some kids from her school stole it. We got it back, but it never ran the same. It leaks coolant and will overheat. We took it to a mechanic and he said it was fixed. He also said it was not a cracked head. However, over the last year it has gotten worse. Maybe it is. Lots of new parts and blows ice cold air.