Problems with a used 2007 unmodified ninja 250

[dcarty57]

So my friend got a used 07 250 mid may and has been sitting because it wouldn't run properly and battery was dead. She's been working on it and I went over to try and help and this is what I saw was wrong.
The bike idled with choke and by messing the the idle adjust knob I as able to get the choke off but the lowest idle I could reliably achieve was in the 2.5-4k range.
I took it for a ride and went through one gears and the rpms would stick. For example in first I'd get to 9k and when I released throttle the bike would stay at a high rpm (say 8k) and stick. Also stick at say the 25-35mph until I broke and forcefully slowed the bike down.
That concerned me very much.
Another issue is the gear shift lever was very sticky, hard to pop into and out of gears. Not HARD but also nowhere near smooth but and proper.
There are also other rpm issues I encountered I can't really remember. It just seemed jumpy while riding along with the extremely strange problem about the rpms sticking when releasing throttle.
Is there a certain reason for all these throttle/rpm issues?
And for the sticky clutch?
Oh and the bike has 13k-18k miles i would say but I can't really remember.
Thanks for any help

Also wrote this on my phone so please ignore my horrible typos

[Ghostt]

Carburetors need to be serviced, I suggest contacting @ducatiman for any carburetor needs.

The cables need to be lubricated as well, I use Bike Aid. Dri-Slide is a lot easier to use than other types of lubes, make sure you do all cables, throttle, choke, and clutch.

The clutch is a wet clutch, so it needs oil to function properly, I also suggest oil change and filter, along with all other fluids.Shell Rotella T6 synthetic is a popular choice for oil for bikes.

[ducatiman]

as described, a potentially hazardous condition, until corrected.

specifically...hanging = internal carb faults...sticking slides or throttle shafts?
reluctance to idle = a clogged idle circuit
"jumpy" RPM's = fuel delivery issue (possible petcock or float circuit within carbs?)

Your carbs need service...disassembly, inspection, corrective action and calibration.

Don't buy into the "add some seafoam in the tank and ride it" type fix....potentially dangerous. Obviously...this bike should not be ridden AT ALL until properly dealt with (carb work) and hanging conditions corrected.