That device helps cold fuel vaporize better when the engine is first started. As time goes on at some point they usually end up stuck open permanently. Aside from maybe a slight stumbling on acceleration with an ice cold engine there are no real problems for worry. If it is still working I'd say leave it alone until you do the intake and exhaust changes. It isn't hurting anything whether it is working or it isn't. For any performance work even on a stock exhaust manifold they are usually removed.
