Help please!! Fortuner plugs...

[Black Sam]

I have decided to change the plugs on my Fortuner 4.0 V6, the ones I took out was "Denso" K20HR-U11, I replaced them with the NGK LFR6C-11 ones, this was recommended by the spares guy, but now the engine has a slight "mis"
Did I do something wrong???? My ignition coils are are "Denso" too, do I have to change them as well?

[Hoppy]

Those plugs sit quite deep, sometimes they get a knock while fitting this closes the gap slightly, just re-check the gaps (1.1mm), check for cracks and re install

[Black Sam]

Thanks Allan, I took them out and refitted the old ones, now running smooth again, I will get the originals from the agents. Sometimes its better to stay original.