i have 1994 dodge caravan.the tranny shifts fine when the car is cold or if you drive then let it rest for 2-3 hours . when its hot the tranny will only run in first gear sometime second but never shifts to 3rd ,please help

Optional Information:
1994 Dodge caravan 3.0

Already Tried:
changed the fluid but not the filter. added lucas trans thats suppose to help slippage