I consume a lot of carbs and sugars in a day. And a vary in weight 3-4 lbs a day. How can a lose a little weight while continuing to build muscle?

Lean body mass. Gaining weight, with a primary focus on building muscle, requires a daily calorie surplus in conjunction with progressive resistance training. Resistance training provides the necessary stimulus for additional calories and protein to be utilized for muscle synthesis. Your goal should be to lose fat and gain lean body mass which may actually increase your weight. Advice: consult a gym trainer.