I have an 07 dbl 2wd with 35K miles. In the last 8K it has started knocking and pinging between 20 and 25 mph when driving conservatively. I had them look at it at 30K and they said I needed the injectors cleaned. So I did that. They said I needed to use higher octane gas. That doesn't sound right. If that is the case, it should have needed that gas from the beginning. They also said I should get the plugs changed. 30K seems kind of early for that. I have read other posts on here where people have said that is when it is recommended. I looked in my maintenance manual and it doesn't call for plugs until 125K. Anyway, it is still knocking after having the injectors serviced. Has anyone else had this problem and what was your solution?