Amazon: 1965 122s keeps breaking down!

[Volvo Guy]

Hi all. I'm having some problems with my Amazon and I'm hoping you guys can help me.
A bit of background: Its a 1965 122s, dry stored from 1983 to 2010 when we bought it and got it on the road again (with the help of this forum). It was used regularly up until a couple of years ago when house moves and babies took over. Its been garage stored since and when I get an opportunity I take it for a run however I don't usually make it back with out a tow.
The car starts well, a bit of choke until it warms up. Set off up the road and it pulls well. After a few miles it starts to miss and hesitate when accelerating. Give it more throttle and it makes the problem worse, feather the throttle and I can get a bit further. When I slow down through the gears approaching a bend, and then accelerate out of the bend, the problem gets worse still and I start looking for a place to pull over. After 3 or 4 of these events, the engine will die and not start. Leave it for 10 mins and it might start, might not so ring for a tow or start walking.

Since the probelm started I have tried a few things.
So far I have:
Fitted new fuel hose and inline filter from the steel pipe to the carbs
Cleaned the carbs, new oil in dash pots etc
Taken distributor to bits, checked insulation around LT lead, new condensor and LT lead, new dizzy cap
Checked ignition timing with strobe
Checked earth strap.

I'll put a new set of points on next and then I was going to look at the coil.
It feels like an ignition problem rather than fuel but I'd like to see if anyone has any other ideas.

Thanks
Guy