[buzzinhalfdozen]

Art, that's not good news. One way I have found intermitent valve issues ie. valve sticking in guide weak spring ect. is by doing a running compression test. This requires removing the schrader from you tester so it doesn't hold pressure, running the engine you will see the needle fluctuate wildly however if you look at it closely you will see where it hits its high number. watching for the needle to not go to that high number at times is an indicater that something in the valve system is amiss. I would think this test would pick up a lifter thats bleeding down as well. As far as it making a noise I'm unsure of the answer to that as the cam is always in contact with the lifter and it bleeding off and not moving the follower, I would think would result in no detectable noise, it simply would not move the valve.On stock engine these problems are easier to find with a simply vacuum gauge as they produce a quite smooth vacuum signal and a fluctuating gauge would indicate further inspection.On the plus side you do have an 02 sensor, that should indicate a mis firing cyl. as a lean condition.