I have been doing a bit of google foo and I think I might need a new IACV.
I have a slight hunt on idle where the revs drop slightly then pick up , drop and pick up.
This is an example of what I am seeing when I have been applying constant pressure. Note it sticking at 1500rpm or so until I tap the throttle? :
Any advice offered?
No real advice I’m afraid but IACV feels like a logical thing to rule out
Tonight’s I did a thing …
Removed the TB
Took off the IACV in anticipation of a new one arriving and reset the quadrant spring
It’s a bit snappy now!
Idle seems good.
Need to put filter back on then get it out for a run to get it warm.
Need to do some work now. 
Work always gets in the way
TL:DR Its still not working. Differently , but still not working.
Its doing this now :
If I ever so slightly tap the throttle it drops to a high idle, but it drops never the less.
I have unclipped the throttle cable from the quadrant and it still does it. I feel its software related so broke out the laptop , can to usb and fired up SXTune.
Of course SXTune needed an update 
There are two settings I can play with that really affect the idle.
If I lower these figures across the board the idle subsides. It never quite gets low enough , but down to 1100rpm from 1300+
When I have reduced the idle air valve position the revs tend to settle better.
I best take this over the RSTuning to take a look!
So, been out today and no change.
I have done the following
The @Steve Swan approach - sprayed some flammable liquid around every mating face I can find - no job
Nipped up ( just in case ) every single nut / bolt I can find
Noted that on initial start its fine , well , slightly high idle but where I would expect it
Backed up the config on the ECU prior to tweaking
Validated that closed loop idle is ON and I have set it to learn idle
It seems to be affected once I have gone north of 3000rpm and its trying to compensate by bringing the revs to 2000rpm , or even 1500rpm and then gently oscillating between those values.
I can feel the car trying to pull me along when around 1800-2000rpm
The rest of the rev range feels fine
Leaning towards : A120E6440S 17.06 11 S2 Elise/Exige Sensor, throttle position, 2ZZ Toyota 89452-35020
Do you have a rpm range where the ecu engages idle control closed loop?
I had an issue once with my idle tuning whereby my closed loop only kicked in at 2000rpm or lower.
As my revs fell naturally due to the timing table, the timing was slightly too advanced for the 2000-2100 area of the table so my revs hung at just over 2000. Closed loop would never deal with it because it was outside of it’s range.
I could fix it by either dropping timing by a degrees or so in that cell, that would make revs organically fall inside the jurisdiction of closed loop or I could expand the closed loop range up to 2500 or whatever. I wanted to avoid the latter, so I fixed it by lowering timing a touch.
I am not 100% sure. I’ll have to have a dig in the settings.
One thing to note though - I have had this working. It’s only in relatively recent times it’s started to fail - and get worse.
I have done some more logging. I can make the engine break up/miss on demand when open on a tiny bit of throttle when I am actuating the quadrant.
This has given me enough of a hint that the TPS is knackered. Ordered a new one and should be here Wednesday
Fingers crossed! Little niggles like this are ultra annoying 
Indeed! I have nearly set fire to the car twice, its so bloody annoying!
Me awaiting the part …
In anticipation of my part arriving I have taken off the old TPS.
I have done a multimeter resistance check and its starts at ~.29ohm and goes to just under ~3.8 at WOT.
I have noticed though that its not a terribly smooth transition when simulating the TPS between .45 and .70. The figures seems to jump and I have a hard time making the numbers go up smoothy. It seems to go from .45 to .51 for example then steps to .58 drops to .53 and then voila , .71 and then I can get a smooth increment right to the top of the values.
Guess Ill only know for sure if its EOL when I put a new one on …
Parts arrived and fitted.
Holding a solid 2000rpm.
About 1200rpm too many.
Booked in at RST to see if they can do some ECU things
I have sorted the idle.
Did a few things with the TPS raw voltage
Still hangs ever so slightly at 1800-2000rpm so I don’t think it will be a wasted trip
Fault found but not fixed
I have a fault with the ground on the IACV. 11.76 ish volts on one pin, but the earth isn’t earthing.
