This cat is only 1 month old. All of a sudden the thing is hard to start, is fouling plugs right & left, blows a little black smoke. At high RPM it's fine. Idle is ok, but it could be smoother. it's the middle rpm range that is troublesome. Gas mileage as went to the dumper. It put a new carb on about 4000mi ago, it ran perfect until last week when this started happening. It feels like it's missing. So I put a new cap, rotor, coil, plugs, wires. It need all that anyway. It didn't help. So in poking arond I see this. Is this supposed to look that way?