The accelerator pedal rheostat(s) tells the ECM what you want to do.
The ECM makes the TB stepping motor run.
The TB tells the ECM where it is via the TPI rheostat.
The ECM tells the UG what it is seeing from the TB.
( I would call it more drive by committee, than drive by wire )

I am not really sure if the ECM runs the stepping motor in reverse to decrease throttle, or depends on the honkin big spring in the TB to do that.

The Ultra Gauge has no idea what the gas pedal is doing.

If you suspect the TPI in the TB, you can remove the plastic cover on it and clean up the contacts and circuit board resistor runs.