I don't know if this will help, but when I swapped my handle bars, i put the brake lever clamp and throttle switch housing too far up the handlebars, thus resulting in my throttle sticking and not returning to idle. When I moved the switch housing back off the handlebars about 1/8 of an inch, the problem went away. Maybe check that the throttle switch housing is not too far up the handlebars, jamming the throttle sensor.
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