I have an '89 Corolla AllTrac with 160,000K which has served me well and is still pluggin along. My question concerns the shift points. With low or moderate acceleration from a dead stop, the trans shifts very quickly twice before I even hit 10-12mph. It then shifts again around 35 and then into overdrive at 45. Should those 1st 2 shifts be so quick? Is there a way to adjust the shift points? Is it determined by computer, manual linkage, or vacumn?