They kind of do that, the lever is not a choke but a enrichining device that lets extra fuel and air in. It does make it run faster and on some of my modified engines I have to raise engagement speed of clutch or tav so it does not take off when starting. You have to let it warm up a bit before turning it off position. If it stalls there is a slide adjustment screw to raise the slide to keep it running. How many turns out do you have the idle mixture adjustment set to? Also when raising or lowering the slide you change the amount of air the engine gets and the idle mixture adjustment must be adjusted. Turning it in richens it and opening it leans it (adds more air) If you can't get it to idle with the adjustment in the range of 1/2 turn to 2 1/2 turns out then you need to change pilot jet which is the fuel supply for the idle mixture.
yeah i have been messing with the air screw at the bottom and that didnt seem to fix anything, while the "enriching device" was on it was going up to like 4000 rpms.. than i would shut it down because that cant be right, which screw would be the slide adjustment screw? and i did change the jets to , main jet to 130 and pilot to 17.5, maybe thats incorrect to change them to that.
I have had a couple of Mikuni's do this. If there is a notch on the cap and it does not sit in the corresponding notch on the carb it will bind the slide. Look at the slide and twist the grip and be sure it is moving freely. For a sticky one I have also taken the slide and sprayed CRC on a cloth and wiped it down just to give it a little help.
The jetting should be fine. I run that same main jet and either a 15 or 17.5 pilot. Mine will rev to 3000 with the enrichner on. If the bottom idle adjustment does nothing keep in mind it us used when the enrichment device is off. Set the bottom screw to two turns out that should get you in the ballpark. I agree with the others either you have a air leak or the slide is too high. Make sure you have about 1/8th inch of slack in the cable when the throttle is closed. If you take the carb off you should see that the slide is closed or close to it. The screw on the right side if you are looking at the inlet opening is the slide height adjuster. The slide should be barely open to start off with. Adjust the screw to get that adjustment.