Having the sensor was kind of a rabbit hole, since I thought it was unplugged. It is definitely a good idea to take a step back and look at the big picture.

A smoke test on the intake will find vacuum leaks that might be your problem. Most DIYers don't have a smoke machine, so you might have to pay a shop to do it.

Hopefully the TB gasket fixes the issue.

 

Just fired it back up and I have the same surge issue. I tested every wire on the MAP, EGT, and TPS sensor (by the sensor) and they all make sense for the expected values.

I think it's pretty clear that the surge is caused by the IACV opening when it shouldn't be, at this point. The IACV is new but could be made out of chinesium, I don't know. I'd like to test that cable going to the IACV but I don't know what those voltages should be. Otherwise if the IACV is good I think ECU is doing some bad calculations and is giving it bunk directions.

 

Is it at all possible that this could be related to the O2 sensor?

 

The 02 sensor reads .03 -> .75 oscillating on the white wire, 14 volts and change on the black wire, and damn near zero on the green wire.

 

What the ****??? The previous reading was with the IACV unplugged just because it was unnerving to be underneath a surging vehicle, but when I plugged the IACV back in (thus began the surge) the white wire stopped oscillating and read from -.1v to .05v.... I saw it jump up to .7v one time in like 5 minutes. what the hell! i'm ordering a new O2 sensor.

 

I'm now realizing that reading could just be due to a **** ton of air going in from the IACV, being a symptom and not a cause. Is this possible?

 

Too much air would lean out the O2 sensor, so the voltage would be low. I'm not sure what direction you should go. With all the work, I'd lean towards the ECU as the issue.

 

Had a similar experience chasing this one down. Only nailed it after the last step.

Replaced throttle body gasket (cleaned surfaces etc.).
Replaced Fast idle valve & gaskets (cleaned surfaces etc.).
Disassembled and checked vacuum control box and all those hoses (cleaned etc.).
Cpu reset etc.

At this point the surge at idle when hot (more like hunting) is still there.

Last step:
Removed and cleaned intake manifold.
Replaced intake plenum gasket.
Replaced throttle body gasket again (may have rushed it the first time and not sealed it properly).
No more surge at idle when hot. That was 21K miles ago.

 

@jljimenezp, what were your other symptoms? was the surging caused by the IACV? as in if you unplugged it, it returned to normal?

 

Never touched the EACV Hunting behavior only presented itself when the engine was warm (coolant temperature high). I'd shift to Park after a short drive, take my foot off the brake pedal and the surging would start.
The check engine light was never an issue in my case (never blinked any codes i.e. CODE 14) so the EACV was the last item on the checklist (worked from simple to increasing complexity). First I checked all the input signals, fast idle and air boost valves. Then came the hoses and connections. Replacing the gaskets resolved the air surge issue *before* I moved on to checking the EACV and its mounting rings.