It's hard to say without being there in person, even being there wouldn't make it much easier though.
If your certain it's the engine it sounds like at least one cylinder or the other isn't doing 100%
Fouled plug or clogged injector maybe?
But I'm just a shade tree mechanic, I'm no expert, I haven't had this problem.
Pulling the plugs is pretty easy at least, I haven't pulled the injectors on mine but I'd imagine that's more difficult
How many Kmh/miles on your NC?
If your a competent mechanic you can adjust your valves and poke around with things out of your way.
If your not 100% certain it's the engine, it's likely chain tension or at least chain related, don't forget to check your tires and tire pressure as well
Either way good luck