Once my motor is warmed up and I have been driving around I notice a slight miss. I will be sitting at a red light and the motor feels like its gonna die then the car leaps forward slightly. It's nothing too terrible, just a minor annoyance. But how could I fix it, and is it robbing performance or gas mileage at all?

I have a near stock 305 TBI from z28, under drive pulley, moroso 8mm blue max wires, pro comp rocker arms.