My montero in costa rica is giving me fits again! Does anyone know how the water lines that go to throttle body affect idle speed?
my idle is at 2k and doesn't lower ever. I have run motor with iac plugged up so no air can bypass the throttle blade and it still idles fast.
This led me to look at how the air was getting to engine and realized it also bypasses blade through the part that has the water pipes in it.

I assume this part is supposed to come into play during cold start and close when warmed.
Could this part(valve) be frozen with rust since my truck only gets driven one month a year? My in-laws also insist on not using antifreeze in coolant!

Anyone have any input, experience with this issue?

Thanks in advance
ps this is a 3.0 ltr v6 engine

 

My 89 had a high idle at cold start. lasted about 5 mins before normalizing. Went on for years getting worse. noticed at 1.2k rpm but over 2 yrs climbed slowly to 2.2K before
I started chasing it. I remember cleaning the tps and iacv, nothing much came of it, but there was a set screw somewhere on the throttle body I changed that caused it to stay high once, before readjusting.
I think the best thing I did for my 89 (and the timing belt broke shortly after) was unclog the egs pipe hole in the throttle body. Had 2 inches of Hash meat" in it. pretty sure that helped my 5 min Idol surge at start up by 75% but never
got around to a new egr valve before the TBlt broke.
Just got a 91 has high Idol at cold start at a WHOPPING 2.4K rpm. Doesn't have quite the same egr set up, or migit recirc exhaust pipe, so, the first thing I'm going for, is a clog in the throttle body throat about 4" inside small marble size from cab side.
or whatever I find on this 91, but it's got it in a bad way.
Anyways, a lot of folks have chased this one into infinity... with no luck, I lost track of others journeys, then mine ended abruptly, BUT NOW I"M AT IT AGAIN HAH NEVER ENDING.