My '90 3VZE-powered SR5 Pickup has a little quirk that I hope someone can explain. I hunted through the FSM and I find no mention of the operation of the VSV that I am about to explain.
When I turn on the A/C the VSV (Idle Up Solenoid Valve) works as expected. Thats a no brainer. But, I notce that when I have been driving the truck around and I DO NOT HAVE THE A/C ON nor have I been using it and I stop to, lets say go into the store. I get back into the truck and fire it up and the idle is fast (around 1300 RPM which is where I have the VSV adjusted to). I pop open the hood and I pull the connector off of the VSV to confirm that it is in fact operating at this point. I drive a few blocks and the VSV shuts back off and all is well.

Is this damn VSV part of the emission circuit as well or what because I cannot find any other reason for a dedicated VSV to be operating in a fashion other than what it's intended purpose is.

Can someone hopefully explain this mystery?