It sounds like you tried to do an engine run before everything was dialed in and ready. The longer you mess around chasing gremlins and running the engine at idle, the less likely it's going to be that the camshaft is going to survive the ordeal. Are you running solid or hydraulic valve lifters? It could be that you've got a mechanical lifter adjusted too tight or a hydraulic is pumping up and holding a valve open when you rev it up. A few minutes' running with the valves a little loose is preferable to the problems you're having, at least for the break-in run. I set the valve clearance .002" wider than specification for a cold start, and ignore any lifter rattle until the cam run-in is complete. It's worked that way for me for over 50 years.
Jerry
