90 WRANGLER.... JEEP IS LEAVING A BLACK SOOT SPOT ON THE CARPORT EVERY TIME IT IS CRANKED, WHEN ITS CRANKS AND THE FAST IDEL KICKS IN IT BLOWS THAT BLACK CRAP ALL OVER THE FLOOR, WHAT CAN I LOOK FOR....POSSIBLE CAT..STOPPED UP...RUNS FINE HAD TO PUT A NEW CARB ON IT, BUT ITS NOT FLOODING.