Well, my problem, same when going on highway. I finally had a message that my transmission was bad at 60,000. After flushing the fluids twice, finally had to be replaced. Really disappointed with the overall maintenance of the 2004 model. It seems like I have to go to the mechanic's shop every six months.
I am debating on what new car to buy. I am afraid I will be spending more time fixing this car. From the first day I took possession of this car, it was a problem. But here I am six running to seven years, I am still driving the dang thing 'coz I love it.