Hi, I know this is a very common issue found on many F4s, but everything I've found hasn't solved the issue.
So, what happens is the bike runs perfect, idles well, goes all the way up to 13500 rpms, pulls doesn't rattle or make weird noises. Temp is always spot on.
Everything is perfectly fine until... after a few hours of riding, especially in traffic, idle starts to be floaty, the bike hesitates, burbles/stutters and tends to stall when I give it a little bit of throttle in gear. If I apply more throttle, the bikes goes up the rpms and goes normally as if nothing happened.

I really tried so many things to fix the issue. Cleaned the fuel system, new oem fuel pump, bought some relacement oem coils (good used), air filter is ok airbox is clean, the solenoid air valve works. Plugs are new and have a perfect brown color. What could it be? Maybe a weak stator that only acts funny when hot? The noise it makes is similar to a too rich mixture situation.

I didn't clean the carbs, didn't adjust the valves. But the bike goes so well when cold or hot that I'd exclude these two: I mean, if the carbs had issues, it would idle rough most of the time wouldn't it? This only happens when the bike is very hot, like at the end of a riding day.
Btw the battery is quite old.