1998 Chevy Truck Throttle Position Sensor

Do not jump to the conclusion that it is the tps sensor or the maf sensor. Blindly changing parts is not good. Test the tps sensor first. The tps sensor is a variable potentiometer, meaning it varys voltage. The ecm reads this varied voltage and adjusts fuel delivery accordingly. A 'dead spot' in this sensor is not likely. To test the tps--with the sensor plugged in--back probe the dark blue wire terminal with the positive lead of a DC voltage meter. Connect the negitive probe to a good engine ground. Turn the key on but do not start the engine. The voltage should be 0.6 volts at closed throttle. Open the throttle slowly and smoothley. The voltage should increase smoothley to 4.5 volts at wide open throttle.
Your maf sensor needs to be hooked up to a scan tool to test. At operating temperature the maf sensor should read 4.0 to 9.0 grams per second.
Testing sensors first will save you time and money. You say you replaced the plugs-wires and distributer cap. Why? These wires are good for 100000 miles. If you used after market wires you'll only be replacing them again in about 25000 miles or so. Were the plugs bad? With these engines always use A/C Delco or GM replacement parts. I know these are more expensive, but they seem to be the only parts that work, for any amount of time, in these high voltage ignition systems.
Test your map sensor. This sounds like it may be the problem. Back probe the light green wire with the positive lead of a volt meter and the negitive lead to a good ground. Turn key on but do not start. The voltage should be 4.0 to 5.0 volts. Start the engine and allow it to idle--the voltage should drop to 0.5 to 2.0 volts. If these tests turn out to be good check back here--let me know how you make out.
Is your check engine light on?

BTW there is no calibration on either the tps or the maf sensors.

 I have never had to calibrate a TPS like that, but your way does make sense. I always use GM parts so the part always exactly fits.
If your engine light comes on then there is a trouble code stored in your computer. Autozone or a place like will scan your truck, as long as the light is on, for free. The next time it comes on have the engine scanned. You can take it to a dealer and have the memory scanned but that will not be for free. Get the code and let me know what it is. If the light comes on for a failing sensor, the computer will not reset the light. The light will stay on until it is manually cleared. An engine light that comes on and off usually means--in this case--a cylinder is randomly misfiring--then it clears up. This problem is most likely mechanical. These engines are notorious for this!
Here are some of the causes--worn out distributer gear--sticking or clogged fuel injectors--failing fuel injector--bad fuel pressure regulator--leaking lower intake manifold gasket--and the hardest to diagnois, sticking exhaust valve. Keep me posted

Hi Blair Blair, my name is Alex and I will be helping you. Here is the information you requested. I hope that this helps, and MAFs are not adjustable. They usually consist of a complex circuit that basically works by heating a platinum wire to around 500 degrees. As your engine ingests air, the wire gets cooled. Voltage is then added to the wire to maintain its 500 degree operating temperature. This added voltage is then read and interpreted by the pcm, and the proper amount of fuel is then introduced for the combustion process.