i have a 2002 suburban 4x4 5.3L and when it shifts from first to second there is a pretty hard shudder that you can feel and a rattling noise coming from the tranny area. the fluid seemed a little burned and dirty, i put in a new trans filter and changed the fluid two times in the past month, each time using 2 quarts of the lucas trans fix along with the regualr ATF. does anyone else have this probelm? or have any ideas how to fix it? also it seems to be fine on cold mornings after about 15 mins of stop and go the shudder starts but only from 1st to 2nd.
please help

thanks