Yes, you must install a new intake manifold gasket.
Replace gasket why does gasket keep sliding
The only fix for a bad intake gasket is to remove the intake manifold and replace the gasket.
No. which manifold gasket are you wanting to replace? Intake or exhaust?
around 6-7 hours according to AllData
Remove the intake manifold retaining bolts from your 1996 Chevy Astro Van. Remove the manifold gasket and clean the surface. Reverse the process to install the new intake manifold gasket.
Pretty straight forward. You must remove the intake manifold in order to replace the gasket.
Elmo is cool
there is no lower intake gasket, only a front and rear gasket
The labor charge to replace and intake manifold gasket, on a 1999 Chevrolet Tahoe, is approximately $180. It takes approximately 2 1/2 hours to replace the gasket.
alero intake manifold torque specs
Repairpal.com