How much coolant is your car using? There is a possibility that the previous owner overheated the engine and caused major damage, but let's not focus on that yet.
First I would check the cooing system to ensure that there is no air trapped in the system. Do this by removing the temp sensor on top of the t-stat housing, cold eng, res cap removed. If no air is trapped in the system coolant will be immediately present.
Next I would test the t-stat. It may be partially stuck closed.
92 Volvo 740 Wagon aka "Mutt mover"