Try the reset but you have a leak. The hissing and improvement after re torquing the manifolds is a clear indication of where to look. I'm afraid you pinched a gasket or it squirted out of place during installation. Just in case I'm wrong, check the IAT sensor and hose that slides on the underside of the throttle body. The connections from Y pipe to manifold too.

I was constantly replacing those cork gaskets. Too much torque and they leak, not enough and they leak, uneven torque during installation and they leak …. you get the picture. Once, I managed to instal them with the gasket out of place on one port. I went stock gaskets with copper spray and the torture of leaks stopped.

Les