I have had a 2000 Chevy Cavalier 2

Hi I have had a 2000 Chevy Cavalier 2.2 liter 4 cyl Automatic for about 5 or 6 years now. I have noticed the whole time I have owned it that when I start the car and shift from Park to Drive I hear a clunk and the with the hood open the engine pivots back and forth one time more than it is supposed to. This only happens from park to drive, it does not do this from park to any other gears, and once the car is in drive everything is normal. The car has no shifting problems at all, no slips or clunking while driving or hitting the gas real fast on take off. I changed the all three mounts on the car yesterday. Upper engine mount (still in decent shape), lower dogbone (tore to hell), and Transmission mount (decent). I really haven't noticed it get any worse over the years I just know its not right. I have never changed the fluid or the filter since I owned the car, and most likely it has never been changed in the cars life. Could a dirty filter, and dirty fluid cause this problem? Or could the linkage need adjusted or replaced? Thanks in advance