Trouble with air leaks

[MinorThreat]

I recently purchased a RT custom with the X-Valve, ULE triger, and ULE mainbody. Looks nice but it has been leaking air down the barrel when I try to cycle rapidly, I have to pull the trigger a few times before it will stop and then it will do it again. I changed the Power tube o-ring but still it leaks. Can someone please help me with this one? Thanks