I have just replaced the timing belt, water pump, thermostat and I still have a problem. HELP!

 

Most common reason for overheating after cooling system repair is air trapped in the system. Bleed air from bleed port near the thermostat housing while adding coolant until a steady stream of coolant emerges.

Other possible reasons in no particular order are 1) malfunctioning temp sensor/gauge 2) collapsed or inner carcase damage to radiator hose blocking flow, 3) blocked radiator (external debris, internal corrosion/scale, etc) preventing heat exchange, 4) leaking head gasket causing coolant to be displaced by combustion gas (loss of coolant).

good luck