Im not sure what is wrong with my car. I have a 08 Chevy Cobalt with 100,000 miles on it. It does not do it all the time just randomly. When driving for more then 10 mins the car begins to jerk. Its almost like when driving at a steady pace Im pressing my break over and over fast but im not. When it does this I continue to drive and it hesitates like its not going to shift gears. I did notice that my rpms stay at 2000 when going 35mph. This is when it starts to do it. I dont know if that has anything to do with it. I have no codes and no check engine light. Every mechanic I talked to says they dont know what it could be and to do a diagnostic test on it. I cant afford to pay them 100.00 to try and figure out whats going on. When I can use that money to fix it. Anyone have any ideas??