Throttle Position Sensor Error

I was surprised to find out my throttle body butterflies rotated 15-20 deg before a signal registered at the diagnostic port. So, I figured I had a bad one and installed a new one, but it wasn't any different. Note, the TPS is spring loaded so you have to make sure to twist it in to load it against the throttle shaft to align the retaining screws.Manual says it should be 0.6 V at 0% and 4.0 at 100%. Not! The new TPS actually came marked for slotted holes but it has fixed mounting screw holes. I slotted them to match the marks and just before the end, so as soon as the throttle begins to move, it registered at the diagnostic port (using Innovate Open Tune II display). You can check with a voltmeter and a paperclip once you confirm the rotation point is being registered.