This jerking just started recently and seems to happen on fast accelaration. I have noticed it once decelarating coming over the hill on 17. It can happen from a standing start or accelaration from lower speeds. It seems to happen somewhere around 35 or 40 MPH. The car seems to accelarate then kind of hesitate then jerk, rpms drop and comes up to speed rapidly. It almost feels like it misses a gear or switches back down then up again. It's certainly not the smoothe throaty accelaration i'm used to.