I bought an Edelbrock Performer RPM intake manifold (carbed) a couple years ago, and installed it with Fel-Pro gaskets (blue seal) and ARP stainless intake bolts. I've never had any luck keeping torque on the manifold for some reason.....every time I checked the tightness, it needed more torque again. I've even had to replace more than a few sets of intake gaskets because they were ripping (probably from the intake walking around). Do you think that the intake could be warped? Or could it possibly be the ARP stainless bolts? One thing more to add......when I bought the intake, I had cast iron heads....even with the aluminum heads I put on a year ago, I still have this problem. Both sets of heads, same problem.....so I'm taking an educated guess that it's the manifold.