Fuel line degredation

[Tryw]

Just thinking out loud, with the problem im getting, (see this thread) http://www.pistonheads.com/gassing/topic.asp?h=0&a... I was wondering if the fuel lines are degrading with the crap that goes in unleaded these days?
Local garage investigated problem before and found some dark goo in the in line filter, but not rust. If this is so has anyone else had problems and if so what grade of line did you replace it with. All opinions greatfully received!