hmmm... welp considering you asked imma suggest yo get the service manual and familiarize yourself with the systems,mainly the emissions and ECU
the only thing that makes this bike even partially difficult is the emissions/ECU components, it's like a computerized system, they all talk to each other nonstop, checking each component is working 100% and adjusting air/fuel mixtures
when you key on and the pump primes and needle sweeps that's the efl check telling itself all is good to go, fire up and be off with your bad self..
IF, something is amiss 95% of the time you will get a CHEK light after the self check meaning you need to pull codes and service said component..
you can get this code riding, like flip your kill switch when going down the road then flip it back on, leave key on.. after switching back to run you should get a "check" in the dash cuz it didn't pass the self check as one or several of the components were left out in the start process, you basically push started it and it's letting you know her this bike didn't start normally... THIS is the check to see of the self check is properly working as intended..
having said that the system can be simple as in a dirty side stand switch to complicated, something amiss in the ECU itself that sneaks by the self check but still causes issues, about 50% of the time it's a sensor something straightforward, fuel pressure/flow so forth..
get the manual, familiarize yourself with the system, and components, go to troubleshooting and follow their steps.. they are very good at diagnosing problems using known symptoms, "power loss at speed" so forth..
off the cuff I would say, check for any codes that mean dealer mode, very simple, around the back seat left side towards the front is the connector, has a rubber cover, locate.. the 4 hole connector that has only 2 wires running into it.. jump with paper clip, tape the exposed areas of clip so bare metal doesn't hit metal and ground out.. turn key on, codes will appear on clock..
start there, if nothing go onto fuel flow test.. fairly simple there..
keep going over the system till it pops up, might be very simple as in a emissions sensor that put the ECU in limp mode or a very difficult gremlin that hides well..
you've performed all the obvious right, spark plugs, air filter, new oil filter, new top grade oil... right? give a general inspection with panels removed, make sure nothing is disconnected, chaffed, broken, split, disconnected, so forth
also is it a SPEED related issue as in when you hit a certain speed, or is it RPM related as in when you hit a certain RPM, how does it cruise over 5000 RPM in 1st? 2nd? 3rd? 4th? 5th? so forth.. is is MPH related, or RPM related?