My 2011 Aveo5 LT automatic with 58k miles on it does the same thing. Is a stable speeds from 40,50,60mph around 2k rpm, has a stumble/hesitation feels like a misfire but i changed the spark plugs, all filters, gas treatment, still does it. No check engine lights. Does your Aveo ever got diagnosed???? Thanks.
Sorry for the late update. Ok took the Aveo to Chevrolet dealership for service. It has 60k miles on it now. Had a transmission flush, oil change and tire rotation. They inspected the car and, of course, they could not locate te source of the hesitation. They recommended clening the throttle body for a lovely 159.00. I told them, maybe next time. I stopped at Walmart and bought a bundle pack of CRC throttle cleaner and MAF sensor cleaner for 8 dollars. A Walmart branded gas treatment bottle for 1.88. Yesterday i took apart the intake air box and hose that goes to the throttle body. The throttle plate and walls were all covered in black sludge. Being careful not to manually open the butterfly (electronic throttle you cannot open them manually), I had a buddy turned the ignition switch on the ON position and depress the accelerator. Removed all the black gunk from the throttle plate and body. Cleaned the MAF sensor. Put everything back and took the car for a test drive. Gremlins GONE!!!! No hesitation. No choking. That was the problem. Throttle body was dirty with sludge. Fixed for under 10.00 dollars.