kneesparks

Hi all, Iv had my bike since sep last year and the past week its been loosing loads of power and getting worse everytime I ride it! Iv checked the air filter and changed the spark plugs and put some nice Shell V-power fuel in it with an injector cleaner and it has not helped at all I was thinking its the fuel pump? The bike idles fine but when you ride and give it full throttle it just dies untill you go back to half throttle Anyone got any ideas? Anything I can check before I take it to the shop? I need it sorted as i miss it and the good weather shold be kicking off soon with any luck