Re: Valve Cover Breather Hose (258-6 cyl)
Are you sure your hooking the hose into the right place?
The rear breather hose should go to the inside of the intake filter..that is, it should see only filtered air.
The front hole in the valve cover is for the PCV valve. It should go to the baseplate of the Weber (basically, manifold vacuum).
I find it very hard to believe that hooking up the breather hose would cause it to run worse....unless you connecting it to manifold vac...in that case, you will have problems.