Overdrive/general transmission issues?

This might be hard to describe, so bear with me. Basically, every now and then, my car starts to sort of shake while making a weird noise and fluctuating in power. It doesn’t feel as bad as that description makes it sound; it’s like it’s trying to shift and then changing its mind, over and over. (it’s auto, of course)… » 5/05/15 9:20am 59 minutes ago