1. Perhaps you try too hard. Are you really relaxed? If not, try practicing being light as a feather, e.g. practice pianissimo, practice being so light that the keys hardly move. I think this is an instance where a metronome will not help, because you are not only supposed to play them evenly, you must create a rythm, a swing. Musically, I think you must make a subtle crescendo. It's a finger-excersise matter, but perhaps even more a mind-thing. The better you can visualize in your head how it must be performed, the easier it will be to do it (if your vision is a good one, of course). Hanon-type excersises will not give you that, in this case. They might help to smooth up your fingers, though..