[Jerryx]

Ok, thanks.

I suspect there definitely is a vaccum leak near the back of the engine. I poked around with a stethascope and with the engine at idle I can hear a sucking sound somewhere back there, near cyl #6 or #5. But I can't tell if it's the plenum gasket or the intake manifold gasket where the sound is coming from.

Which gasket usually fails?

Thanks,
Jerry