My brother has a 2002 tacoma 3.4L, 88000 miles. Starts up and imediately drops to super low idle 300RPM or stalls out. Have to tap idle to get it back. Problem will come and go. While at idle at stop light engine will drop down to 300RPM but will not stall unless AC is on. Recently engine has been getting stuck at 2000 RPG and will stay there until warm. I think it might have something to do with a cold start sensor that is malfunctioning. Thats all thats happening but its a pain in the ass because he cant use his AC or it will stall when he comes to a stop. I don't think its mechanical because if he turns the engine off then on again the symptoms will change.

Any ideas whats going on?

 

Idle air control valve(IAC) needs cleaning,probably your throttle plate as well.Possibly IAC replaced,but I would do cleaning first.

Easy to do,Remove Intake boot,spray carb cleaner into hole on bottom of throttle body just before throttle plate(IAC port) Dime sized hole made into thottle body...open throttle plate,spray ends of butterfly w/ carb cleaner(just enought to clean),whipe out with shop rag/blue towel..repeat again(iac and throttle plate)..reassemble intake tube.start engineand goose throttle,to clear it out.should be much better now.

If you haven't done it in a while its a a good time to clean your MAF.


http://www.4runners.org/writeups/throttle/index.html

 

Thanks for the ideas, I'll pass them onto my brother and I'm sure he'll work on it this week. I'll report back on what he finds. I know my my throttle body was NASTY before I last cleaned it.