[Sriom]

Just for clarification, is it a hard ‘bucking’ under acceleration or just a misfire you can feel? Also, do you have a CEL (check engine light) on?

It's a hard 'bucking' and the engine light is on; solid orange.

 

[Sriom]

Did you perform a compression test when you changed your plugs?
How many miles on the engine?
Did you happen to see how far you reved the engine when you "accelerated hard"

I didn't perform a compression test, I don't have the tools for that.

It's done 166,000 miles. I'd guess I revved it to about 5k or 6k but I'm not sure exactly.