idling problem-fuel accumulator?

any help on this problem?
gti started to stall on idle.
it starts ok but revs too high and then gradually revs reduce until it stops.
can keep it going on  throttle.
changed filter -pump seem seems to work. having a look at accumulator-what a rust heap- i suspect this and am considering replacing!
-but may be wasted dosh if not the issue.

Don't think it sounds like an accumulator problem - is that not just used to keep fuel pressure at standard capacity. Possibly try looking for an air leak.