hey steven, i hve been having this same problem with my 99 3.0 forever now, i just havent had the time to post something up. but i did however ask someone about it, and they said it has something to do with the torque converter, and that is common on all automatic 3.0's.
i also go to school for auto mechanics and i jus did some work on a 98 ford ranger ranger with a 3" lift and 32's, and we replaced the rear drive shaft's u joints, and that however did not change the fact that it was jolting off the start.
if you find out what else it could be, let me know.
1999 Ford Ranger 4x4 Offroad 3.0l
-kenwood head unit
-sylvania ultra white lights
-thrush glasspack w/ chrome 2.5" tip