Forget the old days of carb/airscrew tweaking. Most ECU controlled EFI systems are a completely different ball game. Everything is monitored and controlled by sensors and servos, flow meters etc. Most new bikes are the same and have been for a few years now. Even the 'cleverest' EFI system can't compensate for high compression imbalance.
Going back to the OP, if you have burnt valves which, unfortunately, looks likely, no amount of fuel additive or cleaner will cure it. As mentioned, some good used heads may be the cheapest answer. You could fettle them yourself (decoke, lap the valves in etc) and get them ready to bolt straight on. JMO