I have a 2005 s4 Cabrio. with 65k miles. I was driving on the highway at 75 mph and the engine rpm started bouncing up and down without changing the throttle/accelerator pressure. It felt like someone else was operating the throttle. The engine rpm was jumping up and down by about 700-800 rpm. . I have wondered if the it might have something to do with the throttle linkage or possible the cruise control malfunctioning. I am pretty confident the the auto transmission is NOT the problem.
The car did not provide any error codes. Any suggestions of what could cause such a problem would be greatly appreciated.
Thanks