Throttle Body Service , go to any wshop.. be it road side or a 3s dealership.. No science in opening a TB and cleaning it with Petrol or Carb Cleaner spray!!
Nothing to tune ! just replace air filter and spark plugs if they are weak. Your done..
2ndly, there is no timing belt in Vitz.. Its has a timing chain, which would make noise when it needs to be replaced.