There is a few things it could be. Start with the simple and cheapest things to check then move on.
Lift the tank:
Check the air filter is clean
Pull the plugs check your getting a spark
Change the fuel.
Check you are getting fuel to the throttle bodies
Check all the vaccum lines on the throttle bodies are still connected tight and there is no breaks/splits in the pipe.
Check none of the fuel lines are kinked.
Check any vaccum blank caps are in good condition and not split.
With the air filter off open the throttle fully and try and start the bike, check there is fuel coming from both injectors.
Check the throttle bodies are clean and butterfly flaps are sealing properly.
There is 2 bullet connectors under the seat. With the engine off connect these, turn key in but don't start the bike. Dish should Appear on the screen followed by either -1, 0 or 1. With the idle adjustment knob just left and blow the tank would out. Diag should show 0.
If none of the above highlight the problem check resistance of the injectors should be around 12-18 Ohms. The injectors should show similar resistance if there is a big difference will show there is a problem.
Injectors may not be firing properly, often happens if it's be sat with fuel in for a long period. Some people have tried injector cleaner additive in the fuel to overcome this. Although be careful as too much of this can erode seals
If you still haven't found anything could be
Fuel filter
Ht leads
Faulty throttle position sensor
Throttle bodies need setting up properly. If you have recently bought the bike previous owner may have removed mods e.g. Air filter, exhaust or eprom chips/ power commander and never set the bodies up afterwards. Same if you have fitted Any mods the bodies will need setting up properly.
There are something to have a look at. Define lay have a good look the pipe work and vac caps, if the bike was running fine then all of a sudden became irratic this will likely be the cause.
