Problem With My 2 Litre

I'm having some trouble with my 2litre engine. Little history first, I have just installed it using new Kadrons from the Kaddieshack in the US, built and jetted for a 2l in a bus. Its running an electric fuel pump with an Empi fuel pressure reg set at 2 as per the instructions from Jeff at Kaddieshack. Also running a 009 dizzy with pertronix set at 8 degrees advance at idle. Drove it around the block a few times after installing it seemed to run fine, started first go etc. I went for a longer drive, about 1/2 hour, and once again it ran fine until I drove down a long hill that gets quite steep at the end. About a hundred metres from the bottom it started to drag, put my foot on the clutch and it stalled and would not start again. The dizzy was very hot(coil was only warm) engine was reasonably cool, trying to start it wouldn't even give a cough. A couple of hours later when it was cold it started straight away Revved happily in neutral but stumbled and died when I tried to drive it up the hill. I left it overnight came back to a repeat of the same. It starts straight up revs happily but then dies when I put it under load. The timing advances when I rev it, there is plenty of fuel in it and the fuel filter (new) appears clean.
Any ideas would be much appreciated, Shane.

Check your floats, maybe drop the pressure to 1-1.5. I had Kadrons on my 2054cc and it would foul plugs easily and drown in fuel if they had too much. I ended up running mine in 1psi. How hot is the engine getting? All tinware in place? Could be overheating, vapor lock perhaps? Does this sound like you? http://www.thesamba.com/vw/forum/viewtopic.php?t=561566&highlight=vapor+lock

When were the valves last adjusted?

Valves were adjusted 20 kms ago, engine is not getting particularly hot and although the symptoms for vapour lock sound right it has happened with the engine stone cold and i have my electric fuel pump mounted under the tank away from heat.

Have the mixtures been adjusted and what is total ign advance, I would expect a bit more initial, but maybe the mixtures are way rich, that way it runs cold but once some temp gets into the engine, the mixture becomes too rich. Just because a yank 'set it up' doesn't mean it's right for our fuel and altitude.

Ok tried a few things to no result then replaced the pertronix distributor with an old points one i had and it ran much better. It has less total advance than the pertronix but doesn't stumble under load. Can anybody think why. I have the appropriate flamethrower coil. Also it still stalls when braking down a very steep hill so I think I have a fuel issue there.