I can get it to 5000rpm (but not as often as i'd like) but it does have the tendancy to stall when ive been driving for a while (effectively loosing ALL power) when the car is hot and has been runnig for about 30 - 60 minutes....

Could it be the Silicone hoses clamping and cutting of the air supply or something of the sort??

They do get a bit soft when the car is hot.....

I am running the car on "Motorcraft Double Platinum for escort cosworth" plugs from "GGR"