WOW man..WOW..really? You're just digging yourself into a big hole. The typical "TPS" Throttle Position Sensor, is a Potentiometer. It varies voltage throughout its sweep, its a variable resistor called a Potentiometer, utilizing 3 wires. The 3 typical terminals would be VREF (Voltage Reference), GRD (Ground), and SIG/SGN (SIGNAL).
The Z31 utilizes a single-connector TPS on manual cars, as throttle position SWITCH, and is only an idle switch. 86-89 Automatic cars have a secondary connector that has a potentiometer to show true throttle position for the transmission control module, while 84-85 are fully mechanical. ALL 86-89 cars have the connector in the engine wiring harness, but it does not do anything on manuals. The Automatic TPS has the secondary set wires on it with the connector, but the manual does not. The automatic TPS can be put on a manual car and it'll function perfectly everytime, you can even plug that connector in...but that connector isnt doing ANYTHING.
Source: 1989 300ZX FSM
Don't argue with stuff you don't know, and have just observed on your cars. I've made Z31 engine harness', I know where that connector goes, and its for nothing on the manual. If you get a chance to mess with nistune, you'll also notice it shows no throttle position on Z31 ECUs, but it will on Z32s. It shows "IDLESWITCH" as one of the possible faults.
http://xenonz31.com/reference.html