JAC 96

Hello Please Help I Have A 1996 Ford Explorer Great Suv Has 140000 Miles Never A Problem Untill Now. The Trans About A Year A Go Started To Make A Vibration At 2500 Rpms I Hit The Gas And It Would Go Away . It Started To Do This More Often So I Took It To A Dealer . They Said It's My Torkconverter ?? They Said Its Ok To Drive , Just Get Bad Gas Milelage . Ok So Iam Dr Iving Now Andmy Over Drive Ligh Comes On And Then It Startes To Clunk When I Get Off The Peddle. Or When I Come To A Stop It Shifts Down Very Hard . I Took To The Dealer And He Said I Need A New Trans . But No Codes Came Up When He Put It On The Computer. I Found A Used Trans And Thinking Of Installing It My Self. Ford Said It Takes Them 6hours To Take Out So That Means It'll Tame Me What 12hr What Kind Of Problems Iam I Going To Have?? Computer Rest Codes ? Tools ?? Or Is My Trans Good Just Needs Solenoids?? Please Help Thamk You