Just completed a timing belt, water pump, front main seal, throttle body cleaning and valve cover gasket refresh on an otherwise great running 215K 3.4L in my T100. Upon startup the engine revved to 2000rpm and stayed there. I searched multiple posts about the same problem on lots of Toyota sites and, based on what I learned, was about to pull and clean the Idle Air Control valve, thinking gunk from the throttle body fell into and stuck the plunger while I was cleaning it. That's when I noticed the tiny vacuum nipple at the upper back end of the upper intake manifold showing through the cracked vacuum line that connects it to the diaphragm on the throttle body. 30 second fix and the engine was back to normal. Point is this small vacuum leak showed the same symptoms as the much more involved and much more expensive IAC valve cleaning/replacement. Hope this might help someone else someday!

 

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