Hyundai Repair: Hyundai surges, hyundai sonota, throttle position sensor

Question
2003 Hyundai Sonota, 2.7 liter.  Just changed plugs to Bosch +4 platinum #4418, ran fine for 3 days, now is surging.  Idles fine.  Throttles up then back down, up and down, when at constant throttle position.  Cable slack is fine.  Does not surge with Throttle Position Sensor disconnected.  Checked TPS, 4.4 to 9 volts on full throttle movement, 4.4 volts on constant wire, no reading on middle wire?  Any ideas, I am ready to replace the TPS, but the voltage response was smooth, I don't know what the specs are on this one.  Thanks.

Answer
Something's wrong.  If I recall correctly that this has the three wire sensor, one is ground, one is a 5V reference from the computer, and the third should be the return signal from about 0.5V closed throttle to near 5V open throttle.  At this point, your readings are suspect.  You power wire voltage should be much closer to 5.0V than 4.4V.  And it should be impossible to get 9V if your power wire has 5V.