I have kept a city 2012 for 8 years and sold few months back. At low RPMs, it does not perform well and u feel a sudden push after 3000 rpm. It is due to VTEC engaging/ disengaging at that particular RPM. If this is the issue, then dont worry, its very much natural. However, if ur car has changed its behaviour as compared to how it was earlier, i would say it might be due to choked catalytic converter. Get that cleaned and InshAllah u wud be good to go