I'm not sure where HossHoffer got his info, but there is indeed a setting procedure for the TPS on the 87-90 4.0:
Test is done with throttle closed, connectors connected. Insert probes through back of connectors to make readings.
For manual connect + probe to terminal A, and - to B. Take a reading, which should be in vicinity of 5 volts but probably lower. Note the reading well. Now move the positive probe to terminal C. The reading should be 16 percent of the previous reading.
For Automatic, use the square, 4-terminal plug. Connect probe + to terminal A, and - to D. Note reading, which should be in vicinity of 5 volts. Now move probe + to terminal B. This reading should be 82 % of the first.
Loosen the screws that hold the TPS to the throttle body (carefully, they may be very tight and you don't want to mash the heads or shear them), and rotate the tps slightly to adjust. For finest adjustment, loosen one only a little, and the other more, and it will rock a little in its hole.