How tight should the valve stem be on the EGR valve? Is it supposed to be air tight? My engine idles low and I have low vacuum. While I was looking for a vacuum leak, I sprayed carb cleaner a the base of the valve stem on the EGR valve and the idle and vacuum jumped up. I can see the valve open and close properly when I increase the RPM, so I know the valve is working properly, but I suspect the valve stem may not be seating properly.