i bought my 90 sc and the previous owner said he installed a shift kit in the thans and he never remembered the name. now when i drive 1st gear is really long then it shifts to 2nd and imediately shifts to 3rd. is somthing installed wrong? when its in the bottom of 3rd the acceleration is slow untill the top end of the gear. is there a way to adjust it? or would i have to take it to a shop?