There is no real way to test a TPS. It's basically a potentiometer with a wiper moving on a variable resistor. With use, the resistance at a point the wiper often rests wears and what wears off dirties up the area so the resistance isn't steady and the ECU gets bad information. When the engine doesn't want to work properly, turning off the ignition and running the throttle stop to stop a few times may "clean" the contact point and temporarily fix the problem. If that can be demonstrated, replace the TPS for sure. Otherwise, a TPS problem will not reliably show itself by tests or FI display. Replace and see if it helps is the next step.