I just started to have this problem a few days ago. Im at 22,000 miles. Basically whats going on is I hear a weird noise which to me is a fluttering sound in the engine whenever i accelerate after shifting into 2nd or 3rd. Shifting into 4th and 5th no problems. Now im a novice when it comes to car trouble. Would this having anything to do with the cai filter not being clean (since may). It also has an injen cover over it for water. I wonder if that has anything to do with it. Im probably way off but any suggestions would be good.