Why is my 200 heating up to the 3/4 mark, but after 20 min, it goes back to norm

What is your question?

I've replaced hoses radiator, thermostat oil cooler. I have a very tiny drip coming from under drain on radiator but only leaves ten drops and then stops. I have to ad quart or 2 of water daily . No puddles or leaks other that what I told you. I'm replacing drain plug today and even though I see no drips or hear noises, I'm going to replace water pump and then I e dome whole replacement of cooling system

What makes this problem better or worse?

It get worse until I turn heater on, then it goes to normal and stays there

How long has your 2012 Chrysler 200 had this problem?

3-4 weeks