Trying To Eliminate/narrow Down Possible Idle Issue Causes

@jrichker I did not, I just had the car off and the key in the off position.

So I had been using extra lengths of wire with alligator clips on both ends clamped to the multimeter probes as extensions. When I removed those and touched the probes directly to the safety pin in the TPS ground wire and the negative battery terminal, after a bit of fluctuating the reading settled on 0.8. So I think somehow the extensions were causing the way-off readings. When I check at the 10-pin, it also settles to around 0.8. In both cases if I wiggle the wires the reading shoots up, but it also shoots up if I just barely touch the safety pin, so I can't tell if it's an iffy ground or if it's just the safety pin moving around in the wire causing it.

This is the way I'm tapping into the wire