Plastic phenolic spacer

[vitamin_c95]

So yes, I added one after researching on here about vapor lock. I added a one inch edelbrock brand. Sure, my vapor lock is gone, but I sure as heck cant get the truck to idle smooth. I'm suspecting vacuum leak from gasket or spacer. Anyone have problems getting the plastic spacers to seal? It has two edelbrock gaskets. I've tightened down the carb bolts a couple times thinking they were tight, but don't want to strip the bolt holes or crack the spacer but i sure as heck cant stop this rough idle. Cruises fine.

71 c20 longhorn, 350, edelbrock 1406, aluminum edelbrock intake (both were already installed when I bought this truck a year ago).