PO300-multiple random misfire
i installed a fast 90/90 a couple months ago and i havnt had it retuned yet. it was running fine up until about a month ago. now when i get it into the upper rpms it runs like dog doo and im getting the po300 code. so im thinkingn it needs new plugs and a tune. i could really use your guys opinions, i want to replace the right parts then first time so i dont waste any money. has anyone else had a situation like this? your guys help will be much appreciated, thank you.



