Stalling at low rpms and taking off.

If it was doing it when cold I'd say definitely, but your problem is when warm right? Maybe throttle position sensor? The ICV is pretty expensive ($85 and up). Just to take it our of the equation maybe clean it. I've never done mine, but Googling it, it doesn't look overly hard. Hopefully you have a garage or better weather than I'm having today!!. Good luck. Hey, when you figure it out come back and let us know what it was.

Might be the Brake Booster do you have a CEL coming on?

power curve- power ban only 2 stroke and i find its the overhead cams delayed power supply try ride a kwaka 250 zzr and the overhead cam delay is huge is it similar? The only downside to overhead cams is this yet once they kick in anything without o/h cams will be left behind

check for the pinched vacuum line at the carb,, sportys are hard to locate because they are tucked in way behind , it ay have come disconnected, unless there is a load on the motor it will idle fine, add a little load and you get the feeling no fuel is getting through unless you rev it up

Considering that it occurs more often with the a/c on, it is most likely a problem with either your battery, where it is too weak to sustain the engine output, or with your alternator. I advise checking your battery, and if that isn't the problem, checking your alternator. If neither of those seem to be the problem, its also possible that it is your torque converter, or a skewed setting in your ecu, both of which would most likely need to be checked by a professional.

Stalling is normally caused by a problem with
A) Lack of air - check your air filter
B) Lack of fuel - the fuel filter/fuel injectors get dirty
C) Lack of spark - inspect your plugs & wires
Might want to try cleaning the throttle body. Every 30k miles they should be cleaned.
Best bet however is to take it to a reliable, licensed mechanic. Vehicles 1996 & newer can have diagnostic codes read by a computer hooked up to the vehicle, identifying the problem.

sounds elecrical try some eletronic parts cleaner and spray all the connections maybe the is a [wet] sensor which is hard to trace

Idle Air Control (IAC) motor is sticking.You can try taking it off and cleaning it but most likely will have to replace it.