first off you’re not going to like this suggestion but you asked for it.
dying in first gear and a extremely fast idle? it looks like you have more than one problem going on. Hopefully your NOT trying to ride this bike as it is…I can’t tell you what’s wrong with the bike but I can tell you that if you’re trying to ride it this way you obviously have a death wish….best suggestion I can give..trailer up the bike and deliver it to someone that knows how to fix it…spending a cpl of hundred dollars is better than spending even one day in the emergency room. the real question here isn’t what’s wrong with your bike. it’s “what is your safety worth?”

Your sidestand switch is messed up. You should check its continuity.
Some motorcycles ALSO have a clutch switch — you have to be pulling the clutch.

SIDESTAND SWITCH! you people scare me

Stop playing with the clutch adjustment, it has nothing to do with your problem.

There is a switch on the sidestand that kills the engine if you put it in gear while the sidestand is deployed. Your bike is 10 years old and the switch is probably stuck. Jiggle it loose and give it a shot of WD40 then be on your way.

you need to take it to a repairman dude like a mechanic and get it checked out (are you sure your not just releasing the clutch to fast???) well if nothin works buy a new dirtbike cuz that one is kinda old anyway

are you saying it stalls or it cuts the ignition?
if the bike lurches forward with the clutch pulled in and then stalls the engine, then you need to look at the clutch pack or the release mechanism
If you say you knock it into gear and the engine just dies, it could be the electrics.
Have you tried warming the bike up in neutral turning the engine off, engaging gear and then with the ignition on and theclutch pulled in try push /bump starting the bike. If the bike starts easy and runs off with you then the fault is the definately the clutch

it needs a repair