Your Roush engine was probably built about the same time as mine. The intake gasket failed big time and needed to be replaced.
I also had the
oil leak with the plastic
oil pressure line that madmaxx described. That was resolved by replacing the plastic line with a braided version (you can probably find the thread with parts and supplier if you do a search).
The other
oil leak that I had showed up when the motor was still under warranty. Apparently the oil galley plugs were not installed/sealed correctly, which caused a leak that seemed like a rear seal problem. The clutch also had to be replaced.
If the valve covers have been torqued multiple times, it's possible that the gaskets are toast and need to be replaced.