I have a 2005 Duramax. I've posted a video of the horrible clanking sound it makes sometimes at start up and continues. When it does this the truck goes into limp mode and barely has any power. I can shut it off, plug superchips tuner and change tune, and she's back normal but this is only temporary. The next day or 2 it'll don't again? When normal the injector rates are between -4 and +4 except for cylinder 3 which is at 7. When the truck starts clanking (like timing is off) all injectors rates are 7 and 15. Any body have any ideas?