99.99% of the imported cars have reversed odometers so exact mileage could be any body's guess (i think condition of plugs might give some indication of actual mileage ), here is what you should do :
-- get throttle body and injectors cleaned (see my thread on it ... i did it myself once but would not recommend you .. there are sensors and small seals which are a bit tricky to remove/clean and delicate, if damaged, can cause some expenditure ... my vitz (previous car) with a guaranteed 13000km odo reading (personally imported by someone)had one chocked injector in 6 months due to poor quality of fuel and filters in pakistan .... i did the job with normal carburator cleaner spray and it worked
--- i'm certain this will give you a major improvement, still put some hi-octane .. recommended ratio is 1:4 or 1:5 but for once u may use 1:2 ratio
--- now change air cleaner (genuine only)
--- change timing belt if for some reason u find out that the car has actually done 100k-km or near to it
--- change transmission oil only if the transmission is giving u a prob (like being heavy, noisy, heating, etc)
--- change plugs if required
Lastly
-- do not use any off shelf injector cleaners .. they damage seals
-- if the smoke is black nothing wrong with engine keep compression check option for some other time
-- you can clean CAT, the process is available on net (if i remember correctly xulfiqar explained it in detail sometime ago).. don't think of removing it
---When engine light is "on" the car automatically reduces pick and smoothness, this is a safety feature .. read on net
-- i hope your battery is good as these cars give annoying symptoms on weak battery