Recently purchased 08 Malibu that wasn't throwin heat. It was drove home three hours and ran fine. Couple days later after running it some and cleaning it up before getting to fix the heat it overheated. Radiator was leaking. Installed new radiator and thermostat on the car and flushed the heater core and it'* still overheating and not blowing heat. What to look at?

3.5/3.9/5.3?

Generically, it sounds like you have an air pocket created by a leak....

I agree. Sounds like you have air pockets in the coolant.