I have a 1987 nissan stanza that just got a new rack & pinion and a new bat. when i stat it and drive it around, runs good............. untill i drive for more than 30 min, then it stalls? no puttering or black smoke, nothing it just cuts off. It still has power, but it wont kick over. I have to wait 30min then it starts. This guy said it might be the computer under my seat? i dont want to spend money on a hunch..... where should i start?