Transmission roughness shifting between R-N-D?

[cfmistry]

My '02 4.4i has 97k miles and the fluid in the transmission has never been changed. It shifts as smooth as a dream between all forward gears 1-5. The issue comes in when I am shifting between Reverse and Drive. I always have my car fully stopped (brake in) while shifting between the modes, but recently I have felt like that transition has become a lot rougher. The car is almost lurching (you can at least feel a shake) when I shift from D to R or R to D, but not consistently. Has anyone else had symptoms like this? Any way to change this or just ride it out?

Thanks,
-Cyrus