1. If you are running an edie rpm intake or other tall intake, check the intake side of the valve cover and make sure it is not contacting the intake, I had to 'tickle' the mp black valve cover on my 360 to fit with a tall intake I was running.

2. I have run both the felpro cork gasket and the rubberized metal gasket. I prefer the latter. Although, honestly I have both work fine.

3. Clean the surfaces well, do not over rtv, and check to make sure there is no other interferences with the valve cover, or also a tiny pcv leak that runs down and looks like a vc leak...

Good luck