So, as I have been wrestling with my co2 leakage issue and ripping apart my entire set-up I noticed something. My beverage lines which I thought were 3/16 (I paid for 3/16!) are in fact 1/4" ID! No wonder I was having pour problems. Sheesh.
I can't remember where they came from exactly as I have bought tubing from many places. Never assume you got what you ordered/ paid for. Always check it.