"I was looking at the decel micro switch, and the diagram shows a "Full Load" position. But upon closer examination, that position has no connection to the control unit."
You are looking at the decel microswitch on the car, and the throttle position switch on the schematic. As Steve said, these are different items, in different locations. The TPS is bolted to the side of the throttle body, at the butterfly shaft. The decel microswitch is on the throttle linkage, near the accelerator cable.
'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7