Ok folks, I need some help figuring out a low idle issue on my 2001 Montero LTD with the 3.5L.

Idle is around 500-600rpm after driving for a bit, and it feels as though the engine is missing, but the RPMs don't fluctuate when this happens. Additionally, this occurs when the vehicle is in Drive. RPMs bump back to normal in Park or Neutral.

I notice it the most when I've been driving for awhile and I have the AC on. I'll come up to a red light, and will have to shift the vehicle in to N or it feels like it will die.

No CEL and no codes.

I initially thought it was the MAF, so I cleaned that, and no change.

I pulled the EGR Valve the other day, cleaned it well, and verified that the actuator arm is moving freely. With the engine running, if I pinch the vacuum line off that goes to the valve, the idle goes down significantly, but doesn't die. Same for when I pinch the line coming off the EGR solenoid.

Both solenoids that are connected to the EGR valve measure out at 34.0 Ohms.

The the IAC stepper motor measures out at 33.2 ohms across all terminals per the FSM. FSM says 10-20ohms. I verified the IAC motor vibrated when the ignition was turned to on.

What else am I missing here? What other systems should I be checking?

Thanks for the help all!

 

Cleaning the throttle body and idle air control valve?

 

Well, the IAC is out of spec per my FSM, but I'd like someone to double check that against their info as I am seeing conflicting ranges for the resistance.

The TB cleaning will happen next weekend.