09 Gt650R help

Hi all, I have an 09 GT650R and it’s been great up until now, it happens randomly and sometimes not at all , or the opposite

The bike, mid ride will drop it’s revs, it still runs, but pulling in the throttle doesn’t do much, if I go back down my gears I can get the revs up but the power still isn’t there and don’t wanna redline the revs.

Also, my fuel tank cap sits up on a little angle, anyone elses do this ?

It’s the carby model,

Any help would be awesome