99 Grocery Getter

All right, so my 99 T/A has abour 117K on it. As Im driving on the highway and I get on it the car sometimes shifts to 4th and sometimes comes out of gear and redlines like its in neutral. So im reading that its a clutch pack? if so is it work rebuilding that trans or swap a new trans in

RevGTO

iTrader: (12)

Put it in third and see if it holds third gear fine while cruising without the upshift to fourth. If yes, manually shift it from first to second and hold it in second for a bit. Is the shift tight and does it hold second gear without slipping? Let us know.