So I just bought my first cobalt SS its a 2007 with 50,000 on it and very nice ;however, i ran the codes on it and it says i have a P0300 a random misfire and P0315 the not learned cam positioning sensor, the car runs perfect under load and I just notice a choppy idle and when I tune on the AC it gets even rougher, but when I'm driving its like nothing has ever happened and powers there, I pulled all the plugs and they all look very good no fouling or signs of damage, just looking for some help please and thank you!

 

Sounds like someone replaced the cam sensor and didn't do a relearn. I would have the relearn done and see if that clears up the rough idle. Could also be causing the misfire if it doesn't know where the cam sensor is.