i have a 95 seden with an auto in it.. past few days i'll take off down the road get up about 65mph and it takes a mile or so befor the overdrive kicks in and it gives a jerk when it doese.. normally it would just shift right in over drive when i got to a steady speed.. what all can cause this??

 

well, has the trany been serviced? (fluid chage) .... could be low on fluid and making it harder to shift.

if the vehicle has been serviced the trany may have to be replaced or re-built.... it gets pretty complicated in the auto trany so i won't go there... basically find what seems to be a good used one with a warrenty.
good luck!