Okay, I have a 1996 Chrysler Sebring lxi. A few months ago I was driving and out of no where it broke down and when I restarted the car I saw it had overheated. I immediately got pulled over and got water put in and got it somewhere safe. I then emptied out the coolant and put in the correct 50 50 mixture and tried to get it on the expressway and home. I then realized I didnt have much oil pressure. I put oil in there and then it was fine. I then drove it on expressway and then it wouldnt go over 40 mph because it would not shift out of first gear. The car will drive perfectly fine and shift until the car warms up. As soon as the car warms up it will not shift out of first gear. WHAT THE HECK IS IT!!!

 

When's the last time you checked/changed the transmission fluid?
There are many different fluids in a car and they are all important. They all do different things. Your posting about engine coolant and engine oil is completely irrelevant to a transmission problem with the possible exception that it indicates a possible pattern of neglect.
There are also many possible reasons (other than lack of or dirty transmission fluid) for your shifting problems. If correcting the fluid issues doesn't take care of the problem then you'll need to get it in to a transmission shop for a proper diagnosis. The problem could be electrical, mechanical or hydraulic or some combination. There's no way anybody here can determine that.