340 popping through carb at low RPM.

Well I finally had a little more time to play with the car over the weekend. I started with the richer carb jets with absolutely no change. Removed valve covers and watched all the rocker arms move. They all seem to be moving about the same distance just by the eye test. I then backed off all the rocker shaft bolts to make sure the valves were closed. Pressurized each cylinder and verified no valves are leaking. All valve springs are intact. Put it back together this morning with a different cap, plugs, and plug wires with no changes. Played with the timing a bit and can make it better by advancing it til its hard to start and retarding slightly. At this point, its much better, but I start getting the exhaust pop back at idle. I did this without the timing light today, but have a mark from previous so its in the ball park. Starting to wonder if I should remove the intake and inspect the cam. If it is worn, would it be noticeable on the rocker arm movement?

Thanks for the help guys.