Toyota Repair: Starting engine and ideling, air control valve, toyota camry

Question
I have a 4 cylinder 1999 toyota camry that has 165,000 miles.  It has run great!  Recently, I turned on the ignition, but when the car was ideling, it was a lower than usual idle that felt like the engine was going to die.  I gave it gas, and had no problem.  A few days later, I started it up again, and it did the same thing but the motor died this time.  I turned the ignition on again, and it started.  I had the wires and spark plugs replaced, but it continues to act the same.  I notice when I'm at a stop the idle is lower than usual.  The mechanic wants $105 to do a diagnostic check.  The battery is a bout a year old.  I checked the fluid in it a few days ago, and they were low.  I filled them up, but the problem continues.  Any suggestions would be appreciated.  Hector

Answer
This is usually a sticking idle air control valve that causes this, the valve is located on the bottom of the throttle body. The throttle body should be removed and the valve removed and cleaned with a brush and some air intake spray cleaner, as well as the throttle body, when all the carbon is cleaned from the valve it should work normally, if the valve seems to still stick after cleaning then replace the valve.