+1 for AWD Addict's recommendation. Get your injectors and plugs checked. Misfires at that speed will definitely feel like the car stumbling and fighting itself. Might also want to check the fluid in your diff.
2008 335xi Coupe - Premium|Sport|CA|iDrive|COBB AP|UUC Corsa exhaust|AWE BOVís|BMS DCI|Helix CDV|19" VMR VB3ís|Aero lip|M3 spoiler|ZHP knob|///M pedals|painted reflectors