Thanks Muneeb.
No engine check light, haven't got it scanned yet because i have HEARD and saw on you tube that sensors doesn't give error until they stop functioning, That means sensor might give incorrect reading which causes dis balance in Air 2 fuel mixture ratio.
I learn from that guy video https://www.youtube.com/watch?v=JIu8FX73Gn8&t=14s
i actually left my car to a unknown mechanic, i have doubt that they might have replaced some sensor from my car. That is why it is having this issue suddenly.
interestingly problem is there are 5 sensors that might be causing some failure. 2 x o2, M.A.F, M.A.P, EGR. That confuses me more about how to check or pin point exactly which sensor is creating this mess if IT REALLY IS SOMETHING to worry about.
Well the cat con mesh came removed when i bought this car. I miss that part, although everybody says the same about bad fuel economy after removing it but i think it doesn't make any big change in terms of fuel average. i keep it on 2k RPM and gets almost 8 km/ within city average which i think reborn is suppose to give.
1 question regarding this, Does AC On or OFF really makes difference in terms of fuel average for 1.8 r18 engine?
coming to your last point now, you might be saying right but mine route was from Karachi - Sukkur. it has only 150 km of motorway on which the cars cruises at 100 - 110 only with 2k RPM avg. after Hyderabad it is a messed up national highway, 40 km/h - 100 km/h max on that route. the car needs sudden brakes as well as high RPMs (3k to 4k)to keep up with the flow of traffic.