6.0 Swap Stumbling Idle

[Rich84]

I have put about 1500 miles on it so far. I have had to top off the radiator and overflow bottle a couple times. It has taken almost an additional 3/4 of a gallon of Dex-Cool. Looked last night after about a 40 mile trip and the bottle is down another 1/2 inch. No smoke. It's not overheating. Still running rough in reverse when it's at full temp. Still has trouble with warm starts. Starts right up when cold.
I have other things I want to do to this truck, but not if I have to rip the engine apart first.