What I mean is when I'm shifting from 2nd to 3rd on the left bank of cylinders I can hear a muffled "pop" sound. It usually happens when the humidity is high or it's raining. Also, I detect a little surging under hard accelleration. The truck only has a little over 40K on the odometer, but I've noticed this since it had 17K. I haven't checked anything because it's still under warranty & I keep telling myself I'll get it by the dealership. But the dealership is anbout 60 mi. away.