the car drives ok but slips in 2nd and 4th, all other gears work and when she gets up to speed it drives normally....any ideas?(hoping not tranny rebuild)

 

This condition can be caused by bad seals on the 2-4 servo. This servo is located under a cover on the passenger side of the transmission and can be removed without removing the transmission or the pan (although I would remove the pan to check for other signs of more detrimental problems).

 

how would i test for that?