I'm starting threads, on each unusual problem I'm seeing, rather than trying to fit them all into one. Let me know if this is discouraged, and I can combine them.

This video also shows TP5 reporting an intermittent fluctuation of the TPS sensor voltage, sometimes dropping the low voltage to as low as 0.2V. During much of this video, the throttle shaft is perfectly still and closed. Sometimes my TPS works perfectly, occasionally it acts like this video.

Any ideas on what might cause this?

The output voltage is linearly dependent upon the input voltage. The potentiometer isn't moving, so the resistances on either side aren't changing, so an input voltage shift could cause this. I'd try to monitor the output voltage of the ECM for this circuit, but my multimeter seems to have a very slow response time, so I don't trust it to find a fluctuating value. Has anyone else seen this type of behavior?

The other thing which could cause this would be the load resistor changing it's resistance...I don't know how that could happen, or if it's a common issue with resistors. Or if some other factor was introducing a changing resistance along the wire harness. I haven't seen any evidence of an issue like that. Since the engine isn't running and the van is stationary, I'm less inclined to think this could be the root cause.