Richard, did you find the problem. My car started doing the same thing two days ago. Under load, it would suddenly cut the ignition but then come good again. I can drive it forever on a light throttle and it doesn't happen, but accelerate or climb a hill and it gives these almighty coughs. It's too savage to be a fuel problem, and too savage even for just one HT lead or plug. It's a total (but momentary) ignition cut.
It may not be the same as your problem, but it sure sounds suspiciously like it.
Cheers, Jeff.