I'm having a very similar problem after doing the head gaskets on a 04 4.7HO. The dash lights work, all of the vacuum lines check out, the cable is hooked up to the TB, but still not cruise control.
After the rebuild, I didn't have the cable hooked up properly and I found it loose at the TB. At first, I thought it had moved to set and popped off, but I now think that the TB cam moved and the CC cable stayed in place and popped off. Reattached, but it still didn't work. So I went back in, pulled the battery tray and inspected all of the vacuum lines - everything looks ok.
Can't figure this one out.