Guys, I replaced my Valve covers with supposed OEM replacements on my 86 Z28 and Since then I'm throwing code #54 (EGR). I guess these valve covers are slightly taller the the true OEM ones and thus causing a vacum leak. I built up a little layer of Mr Gasket between the top of the intake and the Base of the EGR but I guess it has not done the trick. Any Idea's ? I guess I'm really looking for some sought of spacer !