Why is my car oil pressure dropping when the car warms up?

What is your question?

I recently bought another GT and I was wondering My GT tends to drop in oil pressure when full heated up It feels like it wants to shut off but doesn't..and when I'm driving it goes up but when I stop at a light it goes back down. And also it idles high when I turn on the heat So I was wondering do I need to change a sensor or something Any help or advice would do me some luck