I have a 1999 izusu trooper 4x4 I won't shift in to 2nd or third

What is your question?

Going up hill and it slipped and would not shift in to 2nd or third or 4th changed transmission did same thing put another transmission same thin replaced computer power /winter switch transmission controhl module still the same this is a 1999 izusu trooper 4x4 v6 cyl

What makes this problem better or worse?

Nothing

How long has your 1999 Isuzu Trooper had this problem?

1 year