Idling at 3k rpms

[jlee29]

I need your help guys
What I have: LQ4/ 01' T/A Harness/ 99' T/A PCM in a 240sx

Problem: Upon start up idles at around 3k rpm's and does not idle down. (I have only let it run for a minute or so)
I am getting the code P0122 Throttle position sensor circuit low voltage (immature)(pending)(old)(history)

What I have done:
Replaced sensors-TPS (cleaned housing before installing new and checked wire integrity into the harness about 12"), IAT, CTS.
PCV system replaced (no leaks)
Voltage at TPS connector on harness is present and sufficient
When scanning via HPtuners TPS % fluctuates during throttle movement
Map sensor is within normal limits (No codes)
Plugging and unplugging sensors, nothing changes it.

Tuning: Completely stock. I only deleted vats, rear O2's, evap ,cags, changed the cylinder volume and engine size to from 5.7L to 6.0L

It runs great with the exception of the idle being high, no other codes. I have not driven the car yet (New clutch and I don't want to be stuck at 3k all the time/ damage something)

[TXZ0603]

vacuum leak?

[jlee29]

Im almost certain it is not a vacuum leak, I have replaced every hose and thoroughly searched.
I am wondering if it has something to do with the LQ4 9.4:1 compression in conjunction with using a Ls1 PCM with higher compression? (I changed the cylinder volume and engine size)
I even re-loaded to original tune and now I am not getting any codes!

[jlee29]

It starts right up runs smooth, rpms 2800 then slowly climb to 3200 and just stays there.. I have open headers maybe that is affecting it? (I doubt it)

[Google]

forgive me I am on my blackberry... What's your t.p.s. Volts? What are your iac position counts?

[jlee29]

TPS Volts are 0%= 0.45v/ 100%(WOT)= 4.33v
IAC positing Engine off =135
Engine on = fluctuation then drop to 0
Engine back off = 186

Any other info need please lmk

[jlee29]

Google* Thanks for the reply! You gave me an idea- I tested the IAC valve more thoroughly and I believe it is malfunctioning, I am going to pick a new one up now and see what it does.. (I tried cleaning the old one, It doesn't move in or out with ignition on, and I cant manually move it either.. hopefully this is my fix *Cross-fingers*

[Google]

TPS Volts are 0%= 0.45v/ 100%(WOT)= 4.33v
IAC positing Engine off =135
Engine on = fluctuation then drop to 0
Engine back off = 186

Any other info need please lmk

if the iac is dropping to 0 with the engine running and then 186 when off then I doubt the iac is bad.. it is a screw motor not a plunger motor.. to test it... plug it in and turn the key fwd engine off.. it should move in and out then stop.. if it does not move then it is bad..

due to the fact that the IAC is at 0 when runing and tps volts is .45v closed throttle, this makes me think you have a vacuum leak some were.. like throttle body area or maybe intake to heads.. this assume's your throttle body hole is stock and not drilled.. you have the stock tb or an aftermarket tb?

[jlee29]

Again thanks you Google* The new IAC completely fixed the high idle! (the old one was seized) Now its a little lopey at around 600-800. And I think I can figure it all out from here .... It is a stock Tb