Bike won't throttle up.

[Tomcat13t]

Just brought my 2001 GZ250 out after winter. Bike started up pretty good with no problems but as soon as I throttle up it died. Put some carb cleaner in the tank and worked the throttle a bit and it started reving up. But it only revs half way and then goes up and down from the half max throttle to a lower throttle over and over. I tried feeding it carb cleaner directly and working the throttle more but I can't get it to go past half throttle. Is there a high throttle jet that won't unclog?

I emptied the take before storing it away for winter but only on idle. Do I have to rev it up while it's running out next time?

Thanks for your guys help!