Peugeot Vivacity intermitent spark! AAArrrgghhh!!!

having a mare trying to figure out what the problem is!
bike wouldnt start the other day took the plug out and was not getting a sparki
by the time i stripped the bike down and tested it i had a spark put it together no spark again
iv checked all the wiring going over bumpes doesnt seem to effect it! i rode all the way to work the other day about 4 miles over speed humps and it ran fine then took ages to get started on the way home and died 3 times on the way back
at first i thought it was the immobiliser there made of cheese in peugeots but this cant be the case as once its started the key can be moved away from the transponder and it wont cut out tested that and my coil by sticking them in my friends bike it ran fine all the connections on the loom look good some were covered in electric greese the only one that was corroded was the connections on the rectifier i cleaned these up but still the same problem
il be riding it might be for 1 minuet might be for 20 it will die! if i hold the throtle open if im lucky it will fire back into life if not i will roll to a stop or it will just back fire and die and i will have to wait about 5 minutes before i can start it again im thinking it might be the stator? any thoughts??

Thanks a lot Chris
its so bad been having to get the bus to work all this week!
FEEL LIKE IV LOST A LEG!