Fred by Drifting of do you mean when you plug tune boy in and look at the sensor page the tps say something like .65 or .68 volts? If so I suspect it has not drifted when you do the ISCV reset on the first click it tells you to see if it returned to .6 volts puls or minus the varience. so you move it nad then click agian it returns and then pauses while it does som thinking in the ecu. then it finaly has you reset adaptives. I think what you see is drift is where the motor nd the cam to the throttle plates could be diferent from many things one being where it was when you powered down verses temps and idle needs. the only time the tps should have identical readings is when the cam is not in contact with the idle arm this is why they never have you adjust the idle arm as there has to be one constant to start from. you move that and you can garantee you just rotated the TPS sending a different signal plu I garantee you just changed that .1 mm setting between the stepper motor roller cam and the throttle plate stop. I hope this is not confusing but it is just my opinion on how these things are working with each other to send the proper signals and motorr commands. I bet Atomsplitter could explain it much better.