Help: 98 Taurus TP sensor behavior

1998 Taurus, 3.0L V6 2V
Drivability question
Engine running at operating temp, tranny in drive, brake applied, rpm around 800 (1000+ in neutral):
The engine intermittently surges at idle. No MIL, no codes. Scan tool shows TP
sensor at 17% (with no throttle applied).
Engine off, key on, back probe the TPS connector: VREF = 5.05V TP = .91V at 0 throttle opening TP = 4.6V at 100 throttle opening
TP sensor table in book shows .65V at 0 throttle opening, but can be up to 15% higher (.74V).
Question: is the TPS bad?
TIA Bill
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I removed the throttle valve assembly and removed the TP sensor. The TP sensor has to be slightly skewed (turned) in order to be installed on the throttle shaft. This is where the 17% is coming from.
Tested the TP sensor while off the car: .55V at 0.
With a test light in the throttle bore, I can see space aroung the throttle plate while the throttle is at 0 position, with the stop tang resting on the screw stop.
New question: should I ignor Ford's warning and reset the stop screw in order to zero the throttle plate? I believe I just answered my own question.
Thanks to all who wasted their time on my stupid thread.
Bill

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Help: can someone else scan TPS on their like vehicle and verify that it is 0 at KOEO (key on, engine off), no throttle position?
I cleaned the throttle plate and bore and set the stop screw so that the Throttle plate is exactly closed in the bore. then overdirlled the TPS mounting screw holes so that the TPS sits exactly at the zero position. The PCM still return 12.5%. However, backprobe of TP sensor voltage is .51 DCV.
Bill

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The processor looks at the TP in ranges ( there are four ranges, closed throttle; part throttle; open throttle and wide open throttle ). Closed throttle will be from .5 to about .8 volts. What you are seeing is normal, which is why you have no code. Look for loose intake air clamps, bad idle control solenoid, bad PCV valve something along those lines. Also if the TP is causing a changing idle you will see it by a changing TP voltage. I doubt the TP is bad.

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Thanks for the reply.
Yes, that what is was thinking, but the 12.5 postion reading through me off. Seems like .51V should return 0.
I did the quick and dirty IAC test: pulled off the wiring harness at the IAC with KOER at normal running temp. The idle dropped to 800 rpms. I will pull the IAC and inspect and bench test (if possible) next.

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