A hose leak will prevent the pressure in the cooling system from reaching the required level; which will lead to overheating. That hose leak must be fixed properly, before the system can be expected to function normally.
If your Durango has the 5.2 or 5.9 liter motor; there is an electric radiator fan next to the radiator. This fan should turn on when the temperature goes up. If it doesn't; the radiator fan relay should be replaced and the fan then rechecked for proper operation.
A worn mechanical fan clutch (used on all V-8s) will cause the motor to heat up at low speeds. I would replace the fan clutch with a severe duty unit
You might find that replacing the thermostat with a 180 or 160 degree unit will help the situation (but the 4.7 liter motor is not recommended for use with a colder thermostat).
The radiator cap must be rated at 18 psi on this vehicle. Many caps are rated at much lower pressures; so you need to make sure the right model radiator cap is on this radiator.
And there should be a 50/50 mixture of coolant and distilled water in the radiator. Running either pure undiluted coolant or plain water will make the motor overheat.