What throttle and what do you mean linear?
The throttle position sensor...
...is on the throttle body (where the air intake attaches to) and it has 3 wires coming off it. To test it, go KOEO (key on, engine off) and use the test leads of a multimeter...
...to read the voltage. It should be 0.5 volts with the throttle closed and 4.5 volts with the throttle wide open. As you open and close the throttle, the numbers should increase and decrease SMOOTHLY. If they don't, then you have a "dead spot" which is a worn out portion of the sensor and that will cause all sorts of issues.
Now if you don't know how to use a multimeter, learn. You can test pretty much anything electrical with one. Your battery, cables, spark plug wires, alternator, any piece of wire on your car, sensors, fuses, whatever. Cost you $20 or less at any hardware store or auto parts store. You don't need anything fancy like a Fluke but in time you may find you will want one. Flukes are ni-i-i-ice...but having *any* multimeter is indispensable when working on a car.
Alternatively, you can also use the multimeter to measure resistance of a sensor on or off the car at the connector. It should be about 5000 ohms with the throttle closed and about 50 ohms with the throttle wide open. Same deal on the smoothness, resistance should decrease or increase smoothly as you move the throttle. Knowing this comes in handy at junkyards to find good USED sensors cheaply if you don't have a way to power the car's electrical system. In fact it's pretty much the only way for a DPFI owner to get a good sensor...
...for now...more on that at a later date
