Your not getting good fuel flow at idle from the carb into the motor . For your choke issue take the float bowl off and look into it . There is a couple small holes that go into passages on the side . One goes to the choke tube where the choke gets it's fuel from . I'll bet that hole is plugged thus your choke isn't supplying fuel or very little when the chamber is sucked empty and will then suck air . You'll need to spray cleaner in that choke tube (the brass tube that stick down from the bottom of carb when you take the bowl off) and make sure the cleaner comes out in the choke plunger port. There also must be an o-ring around that brass tube when the bowl is on , you'll see the groove for the o-ring in the bowl .

Also you'll need to make sure all the o-rings are good and present on the choke plunger , mostly around the tip as it will suck air otherwise even if choke isn't pulled out . Take care of that and you'll likely get rid of the hanging idle . May need to properly jet it once all sealed up and working correct . If your choke is working right it should shut the motor down from flooding out when motor is warmed up and cold the motor should drop way down on idle when it's shut off . There is an area where it'll run either way but not a real long time before the motor is too warm for the added fuel .

I put a std o-ring in the intake boots where it bolts to the head . I can't remember which dash# but it's a little thicker than the metric one so seals better once tight . No need for RVT .

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'86 XT600/3TB motor,,, '88 XT600, ,,'92 XT600e,,, '08 Husky TE510,,, '05 DRZ463,,, '95 KLX650 ,,,'96 KLX650