My truck is doing some clicking sounds, as well as hesitating a lil bit when I give it gas to take off. Once it clicks and hesitates it runs fine. Just when I come to a stop and wanna take off it does that sound and won't go right away even if i floor it! Any thoughts or suggestions? It has a 305. Did a tune-up back in Feb. and rebuilt the carb and radiator 2 months ago. Does not over heat or smoke. Could it be the cat converter being clogged? O2 sensor? Bad timing? Vacumm leak? Fuel pump?