Our Impala's trans recently started to act up with 110,000 miles on it. The fluid is a normal red color and is nearly to the top circle (almost to the top of safe zone). A few months ago I happened to check the trans fluid just because, and it was a full quart low. No problems at the time, I just added a quart of dex and that was it. I'm not sure if it has anything to do with the issue now. I don't know why the fluid was that low, as far as I know there are no leaks, nothing major anyway or else I'd see it on the driveway. I checked the coolant and there is no oil in it (from the trans cooler).
So this is what I have been told it does. This happened twice so far out of a decent amount of driving: From a dead stop, when accelerating the rpm's just go up but you don't go anywhere until a certain RPM then it bangs into gear and goes fine after that. It also downshifted pretty hard when stopping at a light once.
Today I took a look at it and test drove it and this is all I found. Fluid color/level is fine, but when I started it, there is a whine unrelated directly to the engine RPM's in park or any gear. I couldn't tell where from under the hood, but you can hear it inside the car. It sounds like it changes pitch a little when you give it a little gas, but after 1,500 RPM it doesn't change much. When I started driving, the engine and trans was warm. At first I defintely noticed that it shifted pretty slow between 1st - 2nd comparing to my trans (Same trans, 4T65E) other gears probably did too. After another minute or two of driving the trans shifted fine but you could still hear that same whine. That's all I have for now, does this sound like any particular common problem?