Car getting real hot....

64mopar said

Cap does not effect operating temperature.
Low air flow at idle/low speeds,coolant moving too fast through the radiator is the problem.
The temperature will always rise at the sensor when engine is shut down.
It it is not going above 200,that is not a problem.
Was the water pump replaced and with what?

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No, you can’t get the coolant going “too fast” through the radiator. That’s another one of those old wive’s tales that will not die.

If the OP has a 180 degree thermostat and it will climb to 200 it has an air flow/coolant flow issue. Like the pump is under driven.

The faster the coolant flow the better.