Paul - If you check out pages 19-5 & 19-6 of your 28 workshop manual, you'll see the method of testing there. It looks like the range of the TPS is between 4-6k ohms and should read between 4.5 and 5.5 volts. I think that you can take the readings without the special tool they use, just need to make up your own wires...
_________________
NSR300R - Why did i ever have a 250...