Low engine idle on 1999 Toyota Camry

Lately my Camry idles very low when stopped (in gear), making the car vibrate noticably. When in neutral, the idle is a bit higher and seems normal. Can I get the idle adjusted, or do I need to replace the idle air control valve?

Asked by for the 1999 Toyota Camry
I have had great success cleaning the idle air control valve. Many people replace the valve, I remove the air induction duct between the air filter housing and the intake manifold. I disconnect the electrical connector to the IAC valve, remove the two philips head scews that secure the black plastic part of the IAC valve. A small diameter shaft is exposed, turn that shaft gently for and aft, if it feels like it sticks spray "Chemtool" or an equivalent product into the hole in the throttle housing in front of the throttle butterfly while turning the shaft for and aft. You will feel it free up, reassemble, clean the throttle butterfly area of the throttle housing and your problems may be rectified. This works more than 90% of the time for me. Be judicious with your use of the Chemtool chemical it is flammable and you do not want to use to much of it near the throttle position switch as it may damage the TPS switch internally.