Outer Limits 4x4 Board

Engine will not start, appears to have no spark.
Changed the coil and coil lead but still no spark.
Checked most of all plugs and connections under the bonnet.
Fuel pump working but it just seems to just wind over without firing.
Checked power to the coil and appears there is power at the dizzy.
Itched the engine over by just dabbing the key to get number 1 up top and it fired and ran for a few minutes, then I gave it a rev and it died again.
Pulled the dizzy and changed the black module on it with a new one and still nothing.
Any ideas as I'm used to working on perkins and cat engines.

Could be one of the two wires inside the dizzy, which go to the pickup itself. (usually under the plastic cover below the rotor button). These have a habit of breaking inside the insulation due to the advance plate in the distributor moving them back and forward all the time. Causes intermittent no start, and would definitely explain why it died when you revved it - revving increases mechanical advance, so the wires get moved and lose contact at the break.

I checked the wires and they seem okay but changed the base plate with a new one but no luck, so its at the shop now. Hopefully they can find the problem.