Over heating

I have 1994 GEO prizm LSI 1.6L Has 110K miles on it recently started to overheat and water fills up the overflow resrvior and pours over the engine. Replaced thermostat and hoses,flushed radiator done’t know what else to do. It is still overheating,Any suggestion? thanx

Sorry, but I think you need someone with a sniffer to check for exhaust gasses in the coolant.