This sort of thing was happening with mine just last week.

BAD POINTS mate. Pop off that dizzy cap, gear box to neutral turn the engine by hand and check you've got a gap appearing inbetween those points. Mine just had no gap what so ever, would run, but blipping the throttle would cause the same problem you're describing.

They're a $10 dollar part as well mate. Get a new set gap it to .020 of an inch or if you've got a dwell metre which is a great idea too, get those points to about 48-55 degrees.