So I had to remove the throttle body off my 1984 Lincoln Town Car in order to change the leaking pressure regulator because the screws are located underneath the unit. One of the three came out and the other three will not budge. Unfortunetly the last two also have stripped threads. Tried soaking with Kroil, cutting a slot in the head of the screw and they still will not budge. Any other suggestions to try to loosen before I take this to a machine shop?