I have a new limited edition os vspec that I have about 2 qrts on now and I am fighting a high rev before it idles down. The top end runs great but when you let off the throttle it takes about 7-10 seconds before it will idle down. I have tried everything to adjust it and nothing will work. Someone told me the carb could be defective but I wanted to get some input before I have to buy a new carb. The fuel tank is new, clutch and bearings are new, air filter was clean, and fuel lines are new. I also made sure the linkage was adjusted properly as well.