Well, it's been at Merchant Automotive all week. Got the call today they figured it out. When they took the fuel filter adapter off and put the stock fuel filter back on it, they didn't put the check ball and spring back in. They put those in and all is well now.
That stupid adapter was nothing but a pain in the ass since day one. I lost so much time screwing around chasing problems all caused by that thing. Big regret ever putting it on.
Pretty happy I didn't have to pay for a lift pump or a CP3.