Have had problems with car overheating three times-1st time actually melted plastic part of radiator before 50k miles dealer wanted almost 900 just to verify if covered by warrantee. After 1200 dollars in repairs seemed okay but not quite as strong as prior. One month ago again. Repaired hose to radiator manifold gasket etc one week ago after check engine light shows multiple codes for coil to cyl 3 misfire. Told to drive for check engine light to relight and before that it overheated again with a stuck thermostat as in first overheat. Possible head gasket?
It sounds like the head gasket has gone bad. That may have been the problem since it first overheated as the compression would drop and cause a loss in power and misfiring. Even if the thermostat is stuck it is still going to be a problem. Ask to have a compression test done at an independant garage.