I'm going to guess you put some cheaped-out home built intake, or a ragged out 10 year old intake that's been off an engine 5996578568754 times while the previous owners tried to learn to make horsepower, and probably removed the MAF screen. Right? If so, this is likely the culprit as it's not flowing air well over the MAF and/or leaking like a siv.
Could be the plugs too if they're not gapped properly and aren't the proper temperature. What did you gap the plugs to, and how did you gap them? What model plug? Going to guess with "didn't gap them, just put them on" and "I don't remember what plugs they are, just Denso." Likely problem #2.
Finally, how old is the B1S1 oxygen sensor? Going to guess "I don't know, and what is B1S1?" Likely problem #3.