Have an older John Deere generator with a Honda GX390 engine on it. With the idle control off, it runs fine and powers whatever needed. With the idle control on, it runs fine until it idles down. When it the idle control trips to go back to high-idle or full throttle, it spits sputters pops and dies. The carburetor has been rebuilt, carburetor has been replaced with new, fuel lines and tank have been cleaned out, a new fuel shut off valve on the tank, the little choke control diaphragm has been replaced and the check valve between the manifold seems to be working. Any help with ideas of what I need to do to get it to stay running coming off-idle?