My son was driving the car today and said it would lose power while driving with rpms dropping off and the antilock brakes self applying (this is what he said...) then it would return to normal for a while and then do the same. I think it is kicking into limp mode for some reason. I started the car no problem today and then 2 hours later he went to start it and it took 5 minutes to finally get it running. Again no codes. Maybe a knock sensor??????