Folks with Auto Trannys need to reset them ocassionally. The reason is the torque converter goes into lockup based on throttle position and when the calibration gets off it will drive you crazy unlocking the TC when it should be locked up. i. e. Under light throttle an out of cal APPS *thinks* it's at the idle position so it tells the TC to unlock. It will absolutely drive you crazy and until you know better you'd swear something was going south in the trans.