As said, you will have to replace the gaskets again which means you will have to take the manifold back off. If the car stalls quickly are you sure that it is a manifold gasket leak. usually the car will run ok but be a little funny at idle. It should free rev perfectly. Check that you dont have any hoses off, like the brake booster hose, or any turbo/intercooler/idle speed control lines off as this can cause problems.

__________________
Version 6 STI