Thanks for visiting 2CarPros. on this model it's not uncommon for the thermostat housing to leak as the housing can corrode and not seal well.
Purchasing a new housing and sealing ring should resolve the issue. it's important to torque the housing to 18 ft-lb and make sure the housing is centered while tightening it.
These cars were also known for intake gasket failure. You may want to pressure test the system after fixing the thermostat issue to find any other leaks. The guide below shows how to check for leaks with a pressure tester.
Friday, January 11th, 2019 AT 3:34 PM