Sitrep: So I took the car to another mechanic who actually works in toyota. He spent full 3 hours cleaning the spark plugs, throttle body etc. He also took the catalytic converter off and cleaned it well. there was a turbo pipe leaking and we fixed that aswell. After all that the car is doing 9kmpl.
I am gonna have the oil and gear oil changed tomorrow. Oil I am gonna use is 5w30 toyota or liqui moly. Gear oil toyota aswell. Lets see.