By heavy foot, you mean is that vehicle is not responding well on petrol, if that?s the issue then I am very positive that your injectors are clogged.
Removing injectors for cleaning on Honda city i-DSi is not as straightforward as doing this on corolla.
For that, you will have to remove throttle body, ignition coils, intake manifold then you will have an access to the injectors. I know this as I myself have cleaned injectors on my 06 i-DSi as my hobby work. People usually ignore this maintenance as its difficult to access it and once you do so will have a chance cover throttle body and intake manifold as well.
In-fact, mechanic could had easily cover all of them once he was adjusting tappets if you could have precisely requested him to do so.
P.S: Stick to 5w-30, this specific car does not responds well to 20w-50.
2. scanner will not tell you about dirty injectors,
3. you can get in touch with me through private message.