1jz idles real low after 20 minutes of driving

[1jzQuest]

I cant seem to find out what the heck is going on with thing - Its so weird- It starts and idles perfect- runs like a raped ape- but after about 20 minutes or so the rpms will come down to almost stalls out the car at a stop. I give it gas take off and the car drives fine no hiccups until I come to another stop. Now here is the weird part if I pull over and let the car just idle for about 5 minutes the idle comes back up to where it should be. I have checked for vac leaks and I cant find any since I put all new hose on. The IAC is the only thing I can think of that might be the issue. But why would it come back to life just leaving it sit and idle if the IAC was bad. Any suggestions to try guys? Like I said its driveable in this state just dont want to get stranded at a stop sign - lol
Thanks

 

[te72]

Where is your car idling at normally? And when it's idling low? Mine had a similar issue after warming up. My IAC is more or less shot I think, so it could be the same with yours. Seems a common problem with 1j's. I'll let others post up before I give my solution, it's kinda a hack of sorts, but works for me.

 

[1jzQuest]

Car starts right up idles high when cold then as the car warms up the idle levels out around 800rpm. After the 20 minutes of driving she drops to around 400-500 rpm at the stop signs. - When I park and just let the thing idle it almost stalls but slowly but surely she comes back to life and the idle picks back up to around 800 again.

 

[te72]

Definitely sounds like a sticking IACV to me, it may be slowly loosening up (and working properly) as your car sits running for a while. There is a set screw to the left of your throttle body that can be adjusted. This will cause your car to idle higher as you turn it in further (mine idles anywhere from 900-1100 depending on how my IACV is acting that day), however I have been given flack before for "not fixing it properly". Might not be "proper", but try sourcing out a new IACV sometime and you'll understand why I did this.

 

[1jzQuest]

Could it be a failing TPS?
Yea IAC prices are crazy - no way around them if they are bad (sticking) but to raise the idle? The bad thing about them is you cant even take them apart like the 2j's.
thanks for the replies te72