2011 te449 running issue and now starting issue

I've just prepped a 2011 te449 as a rally/adventure bike. Since doing the work I've ridden the bike approximately 100 miles on the first ride,no issues.
Second ride and twenty miles in the bike drops in power and throttle /power is surging, bike when stationery won't rev past about quarter throttle.
Anyway after I was stationery for about 10mins I decide to head for home,I pull off and bike is running normal. Anyway I then decide to try it through some tricky going,bike runs great,as I cut onto a fire road issue comes back jerky throttle ,power coming and going. So I head home thinking that coil or spark plug could be breaking down with the heat.
Once I'm home I change the spark plug. I get the bike hot in the garage and bike seems fine. I then jump on it and try the same ride again. I get about the same distance and it starts again so I think I will head home. As I ride back up a steep hill bike cuts out or stalls(I'm not 100%sure).
Now it gets strange. As soon as it stalled the bike started cranking by itself and wouldn't stop but it wasn't starting. So I turned the ignition key off,the engine now starts? So I turn the ignition on,the bike now stops but starts cranking by itself. At this point I disconnected the battery.
I recover the bike and now back at home the bike won't start. I've checked I've got a spark, I've checked the fuel pump is pumping fuel out of the throttle body supply pipe. Battery is fully charged and bike cranks over great but won't start. Any advice would be great.

I would use a fuel pressure tester and check the actual pressure. It should be around 40psi.