[HI Cobra]

Wayne,

I have a 351W also and went through something similar to your problems
a year ago - after 4 years of running well. You may not have this in
your ignition system but since I do and it was the problem I thought I'd throw
in my solution. On my firewall I had a NAPA Mustang computer chip thingy
in an aluminum case that was about 3" x 5" x 1" that went bad. If I sat
anywhere long enough for heat build up in the engine compartment the
car would just quit. Wait 10 minutes and was fine. We checked everythig
to no avail. It died at a friend's house and we tried a trick he had heard
which was to put a wet rag on it and cool it down - worked fine. I left it
on there and made it home - got the new box and haven't had a problem since.
If you have this type controller it could be your problem. $70 to replace.