Toyota Repair: Camry 2003 RPM problem, accelerator pedal, carbon deposits

Question
Hi,
I drive a 2003 4 cylinder camry with 189k mileage. Whenever the battery is disconnected and reconnected, the RPM gauge goes to zero and does not keep the car on idle run when it is started. It starts perfectly but once you take off your foot from the accelerator, the car just goes off. So far, the problem is solved when the mechanic comes and adjusts a screw connected somewhere to the accelerator pedal. I expected the RPM to just reset itself to the normal idle run of about 700rpm. I changed the battery of recent and this problem came up again. Why doesnt it just reconfigure itself?
Thanks
Paul

Answer
Nothing should be adjusted on either the throttle body or the accelerator pedal. The idle is adjusted by the computer. What you can have the mechanic do is to clean out the inside of the throttle body using a checmical spray and a brush, removing all the carbon deposits usually restores the idle to normal after driving the car normally for about 20 minutes.