Hi, my truck intermittently runs lean, this happens both on fast idle and normal idle. Also it could start running perfectly normal but then in the same drive it would run rough/ lean then go back to running normal again. I think the rough part is it becoming lean because it hesitates (makes that put put sound) on throttle input in the lower rpms up to about 2,000 then it starts to smooth out but a noticeable power loss. I suspect it is a electrical problem because it is the feedback carburetor and it is intermittent.