I’m going to have to agree with Gnarls on this one. If you try to remove a steel stud in an aluminum head you risk the aluminum threads galling and turning into cheese. At that point your only option would be to thread-sert, heli-coil, or replace the head. If the studs are tight I would also recommend leaving them alone. Get some new Toyota nuts and make sure the pipe clamp to the bellhousing is secure and see if it holds. I had the same problem on my 22R. New OEM nuts solved it. Also there are two different styles of nuts. One has a split section o the end. The other looks more like a standard flange nut that has been squished to be a lock nut. You want the one with the split section on the tail.
