My 17 year old son and I just bought him his first car a 1990 300 zx automatic for 800$ . It runs great the problem is it won't shift into over drive when it is supposed to u have to let of the gas then it does some times it seems to work better when it heats up. Now I'm a DIY guy but I no nothing about imports I mainly know about Ford's 351 because of our wakeboarding boat and chevys but I told my son I would learn if he keeps his grades up so here I am doing my home work. By the way the person we bought it from said the tranny was rebuilt a year ago any help off where to start would be greatly appreciated