If its a 5th generation have someone verify the speed sensor is not messed up. With an AT car a bad speed sensor will cause the problems you mentioned and cause the car to switch in and out of gears.

I am hearing more and more stories of 5th gen Accords with speed sensor problems. I really think Honda should do this as a recall, I have a 5th gen Accord myself that has a faulty speed sensor and numerous calls to Honda have yielded nothing.