I've found that if I start out in first and put the throttle most of the way down the selector will actually move from 1-2 and 2-D on it's own fairly prematurely. I can also bump it and move it to the next gear but I have to be quick as it does it by itself. Any ideas?

Also if the car is in high gear (3rd) and I floor it, it will not kick down, just stays in 3rd. Thoughts/Solutions?