The throttle plate shaft is the only thing connected to and causing the TPS to move/rotate to give its reading output.
If there is wear and some play in the bush the shaft turns in, yes, it will have an effect on the accuracy of the TPS signal output.
To test this theory, remove the TPS unit from the throttle bodies and attempt to move the drive end of the shaft in the bush up and down.
If you can detect any play in the shaft/bushing, repair it or replace with another throttle body set, then recheck the TPS signal output on your meter.
This is the only thing I can think of that would cause an issue as you’ve described.
Oh, apart from a faulty TPS sensor itself.
Hope this helps.