trans issue

hi everyone i am new to the sight and was hoping some one might have any knowlage on a problem i am having with an 01 tiburon 2.0 automatic. just bought this car for my daughter and it was fine till about a 1000 miles were put on it . it has 135k on it now and the trans seams to only stay in 2nd and 3rd gear from take off and crusing, i was playing with the shift accuator on the top of the trans and it changed idle and ran fine for 5 min and than started to act up again fulled around some more and now no change. any sugestions or has anyone had this probmle with theirs,