My 512 TR is idling at 1200 rpms when hot. With nearly $3 a gallon for gas, I'd like it down where it should be! I've turned what appear to be idle screws in all the way, both on the air flow meters and in the centers of the manifolds on each side (total of four screws) but with no effect. Any ideas? Or do I just have a vacum leak somwhere.