just an FYI: dont know if this will work for everyone, but it did for me
i finally replaced my chain and sprockets. left the back stock size, but went down 2 teeth in front (to a 14). after doing this the highway starvation problem is gone. now it wont cut out at higher speeds. im not sure if it is b/c it changed the rpm range once you get going that fast, but now i can almost lug it in sixth gear and it wont cut out at all.
could have been one of those "special" cases, but if anyone else still has this problem, it might be worth trying
also, if anyone tries it, and it works, repost, let us know