tryin to break in new engine, ruff idle

I shut it off after 5 min at 2100 rpm because I didn't like how it kept missing every 5 seconds and it would drop 2-300 rpm, sounding almost like muffled backfire.
It does sound like it is loading up...On that link it tells you how to adust the floats also.
Are the plug wires new and What kind?
TXDart