Again, thank you for your replies. I seemed to have narrowed down the problem - from doing some research here and elsewhere on the web - that I am looking at one of 4 problem areas. It appears that Ford had a recall from 1990-93 on fuel pumps and fuel pressure regulators so it looks like :
1) Replace the fuel pressure regulator. If it doesn't work right, then fuel doesn't get returned to the tank and it will boil and the injectors won't run on vapors.
2) Replace the fuel pump - as has been mentioned several times. I will try and check the fuel pressure when I get home.
3) Replace the ignition control module, located on the distributor. It gets hot and blinks out and then starts working again after it cools down-usually 20 mins or so.
4) Insulate the fuel lines, especially the one close to any heat source, ie exhaust manifolds, etc.
I think diagnosing this will be difficult - since the problem is intermittent. It only occurs after driving for an extended period of time and only upon slowing down - the coach just shuts off - dash lights come on - no power. Maybe an ignition problem as the module goes haywire under extreme heat - but if that's the case, then why wouldn't it shut off under load at highway speeds??
Save for the fuel pump, none of these R&R's appears that difficult, and parts are not that expensive. But, there are numerous manufacturers of fuel pumps - any advice? I thought about cutting an access panel in the floor, but am a little anxious about cutting a hole in my floor! I looked underneath and I have pretty decent clearance from the top of the tank to the underside of the coach, but not enough to pull the pump up and out of the tank. I do think that I can just get by with lowering the tank, but basically leaving it in place - anyone confirm this?