porpoising question HELP!!!!!!!

hello, i have a 10 x 6 baby gore hull that is practically brand new to replace my wore out one... the hulls are exactly the same !! i switched everything over( stand , cage , ect) and was a direct drop in... my old gore hull rode free as can be and would slide sideways for ever and was fast!!! the new gore hull isnt as free riding and when it gets planed out and gaining speed it starts propoising like a bucking bull!!!!!!! its has soo much more speed an can feel it wants to but damn it will buck right out of the seat!!! in real skinny water it rides like a dream!! ive moved engine stand back an forward no change.. shimmed the motor no change.. and the bottom from transome forward is straight!! i did notice with the hull on the concrete it has a very slight rock to it side to side... i do not want to run a trim tab if at all possible as the old hull never needed one... would a hull jack work?? an where to place it?? all help an opinions is really appreciated as im all out of ideas!!! thanks , airboat dave