Before taking advice consider few facts
Karachi has absolutely different weather conditions than rest of the country. Lot of city dust pollution and moisture from the sea specially at dawn. Not to forget the rainy seasons April till September where humidity levels go very high. Similarly fuel quality matters a lot. No need to do lengthy and expensive maintenance.
Just clean you air flow sensor with OEM rated spray and remember with electronic sensors don't use Petroleum based cleaners like injector or carb cleaner etc. You should be good after that.
Secondly check the petrol pumps petrol quality which are on your daily route and easily accessible. Finalize a petrol pump that sells good quality petrol and use that.
