My car keeps overheating. We changed out the thermostat, water pump and even bypassed heater core. Am I missing something here?

Hello, when specifically is the overheating occurring? Slow speeds? When stopped? When driving normally? At highway speeds? One thing you didn't mention checking is the cooling fan. If it doesn't work, it can allow the engine to overheat at slow speed driving or when stopped, as there is no air flow to cool the coolant in the radiator. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops