1996 Plymouth Voyager electric problemi think my dad said

Ok my van horn stopped and the cruise control stop and it has a alarm on it and when we go up hills the tranny keeps jumping real bad like kick in gears non stop butwhen we not on a hill works fine then when we go up a hill it jumps and the fan will come on somtimes and the gage will drop to cold then jump to high we have no clue wut is we changed the transmission fliuid and then stuff like that before all this it wouldnt move whne itwas cold then when we changed it the filter was dirty and then no problem but the hills it jas a problem could it be a ground some where or what plz help thank you