Okay new motor installed, use it for commuting to work 64 miles one way for a total of 128 a day, like 3 days a week

black smoke and some soot coming out tail pipe

mods are as follows

.20 bore on 420A, 55mil tb, aem cai, crane #10 cams, msd ign box, greddy header, free flow cat, hks exhaust,

motor runs good, i know gas can be better but have to fix running rich, all sensors were re-used on motor swap, and the old motor had 252,000 on it

so questions are

1. where to begin trouble shooting for black smoke
2. what plug should i use in this car, i perfer a denso but local joints do not carry

all help and plug thoughts would be great, hoping to fix today

plugs, use stock temp NGK's unless you're turbo or high compression then go one heat range colder.

for your rich running problem, are you throwing any CEL's?

no cels what so ever or this would be easy

are you running a cat?

yes it is a free flow cat and i just passed NJ inspection 1 week ago