Have Toyota Questions? Ask a Mechanic for Answers ASAP
who installed the idle air control valve and throttle position sensor? Where they Toyota parts? Are you getting any warning lights on in the instrument panel? Do you have an active testing scan tool to drive the idle control motor up and down?
Without having any test equipment is difficult to tell you for sure how to proceed. One thing that you can do that won't require much equipment is to remove the intake boot which requires a 10 mm socket. Once the boot is disconnected from the throttlebody make sure there's no carbon buildup around the throttle plate. Clean that with carb clean and a clean rag. Then remove both the battery cables for about 10 minutes. While both cable ends are isolated from the battery take a jumper wire and connect the two cable ends and wait 10 minutes. Remove the jumper and reinstall the battery cable ends then start the vehicle up hold engine RPM to about 3000 RPM until it clears out. Then reduce the throttle to see if it will idle once it's warmed up. Let me know how this goes. I assume you've checked for intake leaks and anything as far as the cabling that would keep the throttle from returning to the full closed or stop position. There is an idle stop screw that is held on by a small 8 mm nut and threaded bolt. Make sure that has not been monkeyed with. Also it is critical that when the throttle position sensor is installed that the IDL points or idle points are in the idle position if the sensor is not adjusted correctly the idle will not self-correct itself. The computer thinks you have a light throttle and not close throttle.