I have a Q45 infiniti 2002 code p0300 came up does it just need a tune up? on 2002 Infiniti Q45

when idle its fine under load is when it misfires .

Asked by for the 2002 Infiniti Q45
it could need tune up coils or insulators. it could also be fuel related
where do you recomend i start so i dont waste so much money?
with all do respect seek a mech opinion on the issues otherwise we are guessing. look for a good AAA approved repair shop in your area
thanks for your input.