I have a 2003 i4 with an automatic. When I drive down a flat stretch of road at around 37-38 MPH with the RPMs around 1750 the RPMs begin to oscillate. The engine speed drops to 1700 then back to 1750, drop to 1700 then back to 1750, etc. This occurs in roughly one second intervals. You can feel and hear this oscillation when it happens and you can watch the RPM needle moving back and forth. Has anyone else heard of this problem? Let me know if there are any other details I can give.