The fluid was over filled and looked old, that's why I changed it out. I've filled it now since the filter change, to right at the fill mark. I'm debating on whether or not to add another quart to put it back to where it was, or maybe a transmission additive. If I'm putting the rpms to it when it shifts, its fine. If I slightly accelerate, just enough to rev up enough to get through the gears it fluxes, and jerks. If I hit the brake while driving, about 1 sec after I release, it clunks again, everytime. Could this be a torque convertor thing? Is it possible that the fluid drained out of it? I was told that a drain and filter replace wouldn't get the torque convertor fluid out, a flush would be required for that.