Mitsubishi L300 Carby problems?

Hey folks. I'm hopin' somebody out there knows a bit more about motors than me and can give some useful advice...
I've got a 1984 L300 Express van. She's fairly rough & not really worth throwin' much money at.
Here's the problem: she always starts from cold on 1st or 2nd attempt, but once running will unpredictably stall at low revs. It rarely stalls when idling, but often stalls at junctions etc. Once stalled it generally takes at least an hour before she'll fire up again, which can cause problems at roundabouts & traffic lights!
There's always a strong smell of petrol when it stalls, which makes me think its flooding.
Anybody got any ideas?