Your car WILL backfire if it's cold so that's normal. This also can be a missalinged camshaft,or a bad tune. That's what you will encouter mostly in backfiring
it is your curberator u need to get a guage (AFR guage found in the catalog and then tune it). It is to high, your afr is high, so you need to get a screwdriver, look for a screw below the airfilter and scroll down. If you dont have a guage scroll down until there is little smoke from exhaust