Right then, it's probably electrical so I'm lost... hope someone can help:
Riding along quite happy, then the engine starts to pop and misfire.
Shortly after, the engine is on/off, like surging and dying repeatedly.
Pull over and it dies.
Re-start her and tickover is as smooth as yer bum, but slowly increase the revs (in neutral) until it gets to around 4k then it dies. Release throttle and it catches again at tickover and it ticks nice n smooth.
Leave it 15 mins, fire up, ride off - all fine and dandy again.