Was it sluggish before replacing the spark plugs? I've got a 2020 also with the v6 with a little over 21k miles. It's always run from day one like a scolded dog when pressing the go pedal. These 3rd gen v6 tacoma's have been noted in the past for some running a lot better than others with no reason to be found. Need more info how sluggish this truck really is...if a lot, or just seems slow what you've been use to. I can tell you a friend that had a 2019 trd...his truck never ran as good as my 2020 sr5. It drove him crazy after 2 dealers told him he was crazy, nothing was the matter with his truck. It pissed him off to no end that he traded the tacoma in for a frontier.