Valve cover problem

Hello everyone, I have a late model 350 chevy. I replaced the valve covers and the engine runs rough and dies. I have swapped them back and forth and have narrowed it down to the valve cover with the PCV valve.(the passenger side) If I put the old valve cover on that side it runs fine. as soon as I switch to the new valve cover it sputters and dies. I am using the same PCV valve with both covers. Any help would be greatly appreciated.

Thanks,
Dave

Any baffles inside the valve cover ,hitting a valve?

Thanks, that's what I was thinking. I removed the baffle and it seems to run a little better. But its still idling rough, it's not dying though. I don't hear any noise (before or after removing the baffle) and I dont see any wear spots where the rocker arms would hit. Would it make a noise if the rockers hit the valve cover somewhere?