Well I found the problem!! I took the back valve pan cover off and found that one of the rocker arms on #5 cylinder wasn't tight. I used a cheap torque wrench and also forgot to give them an extra 30 degree turn per the spec. Got it back together and started it up ... ran as smooth and quiet as it ever has. Now I need to pull the front valve cover and retorque the front rockers. Thanks for all the suggestions and help.