My truck 03 has been been lacking power for some time. I replaced the ficm and that seemed to help a little. Now I have two injector codes. Injectors 4 and 6 I think. The code says something about cylinder contribution. I was wondering if there is an injector rebuild kit. What generally causes the injectors to go? The nozzles wear out?? the electrical gets a short?? Also how does the numbering on the injectors relate to their installation in the truck? are the even numbers on one side and the odds on another? Thank you very much.