Ford V10 engine surging idle and power , help please ??

I'd be very suspicious of a massive vacuum leak. Vacuum not only controls the idle-air-control valve, but also the EGR valve and even the fuel pressure regulator. The soft vacuum lines (like elbows and even some of the short vacuum lines) are rubber which gets brittle and cracks over time. And, for some reason rodents find the plastic vacuum lines tasty.