There used to be on on Rt1 called cycle sport but they closed down over the winter
Don't know of any others though. If you needed a second look I'd be glad to try and help. If its an older carbed harley, idle problems are generally fairly easy to diagnose. Either you're not getting or getting to much air, not enough fuel, or not enough spark. In the past for me on my bikes when i have an issue like that it's been a bad seal behind the throttle of the carb where air is leaking in.