I recently purchased a midnight blue 2001 Grand Marquis LS, with the 4.6 sohc V8, rated, I believe at 220hp. An awesome car. I took it to Ocala, Florida within a week or so of buying it, about 2500 miles round trip and it performed almost flawlessly, with the exception of a little "chugging" under light acceleration at about 45mph. I have been told that this can be rectified by changing the fluid in the tranny and the torque convertor. Any comments?

do you notice if this chugging is when the car is trying to shift?

it only does it during gradual acceleration