Last night I fired up my second UDS and I had a bit of a problem with temps on it... but I think I know why. I used a ball valve that I had around the house. It fit the 3/4" nipples on my UDS BUT even though the threads were 3/4" the port was only 1/2". Aha! Not enough intake.
See the valve on my other UDS was full port or at least it was bigger than the hole on my other one.
So if you are having problems perhaps that might be a clue for you. Just a thought.