intake gasket or valve stem seals on the passenger side head is where I would start AFTER I do a compression check. What are the odds of you installing the rings wrong on 4 pistons on the same bank of the engine but getting them all correct on the other bank. Slim to none. With the engine running spray some carb cleaner on the manifold where it mates with the cylinder head and see if the idle changes, if it does you found your problem. If it don't you might wanna look at you valve stem seals.