Hi

2012 is it not under warranty ?

Does the fault code clear ?

Micra's had in issue with fault rear sensors effecting front sensor,(and flagging front sensor code) not sure if this was fixed by 2012.

I had a 2006 with rear sensor fault effecting front sensor and with poor running and not flagging any faults

Try scoping front and rear sensors to see what is happening , also try running with rear disconnected see if it fixes the hesitation fault

cheers aidan