So recently my car (04 Acura TL Automatic) has been having strange problems. When I start the car and get going and pick up the speed, after a while, I experience a weird sensation and a sound on the driver side of the floor. It is difficult to describe, but it sounds like something is switching, like gear. The thing is this happening rarely, it happens before 60km/hr at the lower speeds and it only happens once since I start the car. If I slow down to a stop and speed up again it does not have this problem. I'm suspecting it is a transmission thing because I felt the something that feels very similar on the back seat of a 2012 Dodge Ram while it was changing gears.