My 2014 1LT has been virtually problem free. Heard more than normal ticking today, decided to pull dipstick and check new oil, reading is spot on. Noticed an immediate whistling noise from the filler tube and clicking from the valve cover, like something is slapping around. The Idle actually changes when removing the dipstick, and when replacing the dipstick the idle drops and the motor shakes like its going to stall. What can this be? Runs fine with no hint of noise or any engine problems?