Look for any vacuum lines that are damaged, split, or perished. Look to make sure that all openings on the manifold are closed.

 

Make sure the TB is in good order and that it shuts all the way.

 

Look over the alloy cast manifold, castings are known for cracking. Especially around the bolts where it mounts to the head/tvis plate. Make sure the manifold is installed with the right gasket too. Inspect the tvis plate too. It might crack or leak somehow.

YEWWWWW!

 

after almost giving up i found and old thread that covering up a hole in the throttle body works... and it did!

 

cheers for all the help everyone much appreciated :)