Why does everyone have to touch a car that is working perfectly? And the other thing is, why do you take your car to a mechanic when they have absolutely NO IDEA how to work on this model, which means they have no service manual? I am sure it is either two things.
When he worked on your throttle body, he either 1.) Did NOT replace the throttle body gasket that goes behind it OR he did not bother to put it back in, if he removed the throttle body, and now there is a vacuum leak that is causing the ECU to compensate the air/fuel mixture by raising the RPM's. If he did NOT remove the throttle body, then he used a cleaner spray, such as carburetor cleaner, that might have affected/damaged oxygen sensors, catalytic converters and other sensitive sensors.
2.) When he was removing the throttle body, he has disconnected some vacuum hoses or other emission related hoses and forgot to put them back on. You should check to see if anything has been removed or missing and check again.
Also, why did you have your spark plugs changed? The original spark plugs will last for 130,000 kms before the first replacement is needed. They were NGK Iridium Tipped and in Japan, one spark plug is around Rs. 4,000.
See if the things I mentioned help you out and then let us know if you have sorted it out.