It's just a pair of switches. One tells the ECU when the throttle is closed (idle) and the other tells when it's wide open so extra fuel can be added for full acceleration. Unless something is broken, you can adjust it. For the idle switch, it should switch from closed to open at about 900 RPM.

Dave

 

I wouldn't worry about the Throttle Position Switch so much as the Thermotime sensor and other sensors on the front of the motor. Make sure they are clean of corrosion, because they can produce false readings and cause the car to run great/crappy when cold, but when they finally warm up they run the complete opposite. Also check that the Air regulator is working properly, because that can throw things off too. it would help to buy a Haynes manual as most of the ways to check these things are in it.

The way to check the Air regulator is when the ambient air temp. is below +/-60° the valve should be wide open and above that temp it should be closed. The valve is the disk shaped think on the Intake manifold half-way back on the drivers side. Pull the hoses off and look inside with the motor cold and you should be able to see through, when warm you should not be able to see through. If it is gummed up then try some carb cleaner to clean it out.

Good luck,

Aren77z