Q: Got the water pump replaced but still leaking and heater is now going in and out and its still overheating ! Why?

This engine has problems with the intake manifold and cylinder heads that will leak over time from the metal deterioration in the coolant passages, eventually causing it to leak either at the corners of the intake and heads or into the engine causing internal bearing damage. The heater goes in and out due to the coolant being low and the air in the cooling system not transferring heat to the heater. Have a mechanic, such as one from YourMechanic, pressure test the cooling system to identify and locate the coolant leaks to see if the intake and heads are leaking in the corners. They will be able to diagnose your overheating issue and let you know what repairs will be needed.