Found what is the source. I don't know why I decided to try this but I desperately started disconnecting sensors and switches at random hoping to find something particular when idle was surging.

The blue wire that goes to what I think is the power steering switch, when that is disconnected at the connecter (single wire) the idle problem goes away. For good! Reconnected and the problem will come back.

Maybe the PS switch is bad or there's a fluid blockage somewhere.

Anyhow, before getting to this point the following parts were replaced in the past 3 months on this problem:

1. throttle body
2. MAF
3. diverter valve (2 of them)
4. IAC
5. EGR valve
6. EGR solenoid
7. PVC valve and plumbing
8. vac lines
9. two sets of spark plugs of different heat ranges and gaps
10. maps on ROM to stock (fixed some other problems with this one)

Also pressure checked MAF, charge, rocker cover, and sump for leaks, performed several compression checks, checked the fuel supply and regulation system, the purge system, master cyl system, all 3 FP relays, and the FP resister module, not to mention interlock switches and position sensors, openport cable, fuses and other fuses, circuits, modules, O2 sensors, and relays. I was beginning to be convinced it was code related or a chaffing harness.

I must have consumed a grand total of over one hundred 12oz Seirra Nevada porters, about one dozzen Corona's, and several Heineken brews while on this project alone, so I spent over $250 on energy/hydration suppliments. All the parts were cheep or free spares I have accumulated over time - good to have at times.

 

So im bringing this back from the dead. Im having similar issues and im not sure what it might be. OP do you have any updates?

 

I am also having the same exact problem. I am going to try reseting the idle with disconnecting the battery then reconnect it and let the car idle for 10min's.

My idle from a cold start is perfect. Car drives great till it warms up. Then the idle bounces around from 1k to 2k. I checked and cleaned the TB and IAC. Car has zero vac leak's.

Car drives great when I first turn it on and drive around =-\

 

mine does the same thing bump to this thread but my car has aem ems and my wire is no longer connected to the ps pump any input guys.

 

heres somethin by chance doesnt look like you checked? did you inspect the tps(throttle position sensor), do you by chance have ecuflash? that way you can check and see what voltage the tps reads at idle and cruise load %??, obviously you checked that other stuff and said you replace the tb, you sure the tps was installed in the same spot correctly? theres my 0.02 good luck