Putting this up in the off chance that others have had this issue; this one has just popped up for me.
327,000kms on the clock. Completely standard. Idles at 850 rpm on the tacho.
First thing in the morning, when the engine is cold, get about 1km down the road to a 50km/h section that I depress the clutch because of those painful "3/4" style speed humps.
Monday morning, idle drops down to just under 500rpms, nearly gets to the point of stalling, but recovers ok and idles at 650-ish rpm. Hmmm, annoying.
This morning, same section of road, depress the clutch, stalls straight away, doesn't ever try to recover. Right....hit the key to start it up again, no problem, idles about 750ish rpm.
As the car comes up to temp a few more kms down the road, idles lower, but not as bad when the temp was cold cold. As it warms up, gets back to normal idle speed of 850rpm. Fully up to temp, no idle issues.
Apart from checking / topping up oil, only touching of the engine has been some cleaning of electrical connectors to help eliminate another niggle it had some months ago. Only gets driven about 150kms per week though usually.
I have a couple of things I am going to try:
The most important and easiest thing I am going to check, is that the crank pulley does not move side to side when the clutch is depressed with the engine running. If it does, it will need a rebuilt motor. No question.
1) Connect with Consult, check and adjust base idle speed and timing if required.
2) Check and clean the terminals in the IAC terminals and plug AGAIN (I actually may replace the plug and terminals on the harness side, I bought new ones not long ago)
3) If no luck with 1) and 2), adjust the throttle hard stop on the throttle body (yeah yeah, band aid fix....there is a reason for this however)
4) Disconnect the AC drive belt to see if there is "resistance" from the AC compressor, even when it is switched off.
5) Find a good IAC valve, clean it up and swap them over. I don't really want to do this, since it's a PITA and I don't really have time. Or, I spend $170 and buy a new one. Only problem with this, is that the fast idle valve sandwiched between the IAC valve and the plenum is not available as a new part, and I would have to swap in a cleaned up used one at the same time)
If you have had this same issue...let me know!