Originally Posted by maddog34

"The other thing I have noticed, when I shift to a smaller cog, occasionally it will get easier to pedal 1 or 2 strokes before it engages. It is not consistent and I hear it shift, I can’t figure our why it does this. When I put the groupset on, I installed all new cables. I’ve put about 500 miles on the bike since I built it, and it does not do either issue in a bike stand."

sounds like a Freehub Pawl engagement issue to me. they can be quite random.
there's a chance enough grunge has built up on your cassette to cause this, but that's usually only on an MTB...How old is your chain? check it for wear or have someone do so that is qualified. If the chain and cassette are ok, then it's definitely the Pawls in the Freehub not engaging consistently.

try this quick test.. lay the bike on it's left side.. shoot a "psst" (a few drops) of penetrating oil into the freehub's center... clockwise spin the wheel for a minute or so..... go ride the bike and see if the skipping still occurs...