Q: What else can cause an over heating engine. .

Overheating in stop and go traffic can be due to non functioning electric radiator cooling fans. A poorly functioning water pump can be a cause, too, for example if the drive belt is not tight enough. If the car is overheating and, at the same time, you have inadequate cabin heat, that can be due to low coolant level, trapped air preventing adequate coolant circulation to the heater core or other faults such as a plugged heater core (it’s hard to say if the cleaning you describe was successful). There are a few other common causes of overheating, namely a faulty thermostat (inapplicable in your case although be sure you used a genuine OEM thermostat), a plugged radiator, collapsed hoses, non functioning cooling fans, and a faulty water pump or drive belt. Certain engine faults, such as a leaking head gasket or poor engine running condition can also cause overheating. If you desire that this problem be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an engine overheating diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.