I hate the fact that I need to contribute to this topic but...
I have a '93 Imperial with a Ford 460. I have had similar problems to what Lil Truckr described. I think that I found the problem, (at least part of it) on mine is the knife switch on the negative side of the battery.
I was driving down the road and lost power, the horn honked and then the engine died. I suspected the switch, jumped out and moved it, never opened it though. As soon as I touched the switch, I had power again.
Im not sure if this is normal,I have only owned my RV since October, but with mine, when the switch is closed, the horn honks. That was my indicator that I had lost battery power.