Toyota Repair: Cold Stall, air control valve, toyota 4runner

Question
Hi,
Vehicle information: 1999 Toyota 4Runner, 4 cylinder, auto. trans., mileage: 104000. I checked for CEL code and nothing came up.
Problem:  When the engine is cold it starts up fine, but will not idle.  I step on the gas and the RPM goes smoothly up, and when I let off the gas the RPMs will slowly drop down until the engine stalls out.  This problem started after I let the vehicle sit for two weeks of non-usage (I drove my other truck).  Once the vehicle warms up (needle moves to normal area on temp. gauge) the problem goes away and the idle is normal and the vehicle doesn't stall.  I tried removing a battery cable to reset the computer, but this doesn't help.  Thank you in advance for your answer.

Answer
The first thing I would recommend doing is to clean out the inside of the throttle body using some spray intake cleaner and a brush, if that doesn't seem to help remove the throttle body and then remove the idle air control valve (IAC) from the throttle body and clean the inside of it as well, these are usually the causes for stalling. When the IAC vlave is off you will see a small sliding barrel valve, this valve has to be able to be moved open and should go back to almost closed by itself, if it's sticking after cleaning it then it will need to be replaced.