I've noticed while driving my 93 mustang (132000 mi) the trans will not shift back to 1st after coming to a stop while in overdrive or any gear. It feels like it's in neutral. If I give it 4-5 seconds while slitely pressing the accelerater it will shift into gear and take off. I've changed trans fluid and filter and I still have this problem. The trans shifts great out on the road after it gets going, it's only during stop and go.What do you think could be the problem? Thanks