truck through two codes today for cylinder contribution/balance faults....P0278(cylinder #6) and P0284(cylinder #8). Truck was cold when started, idled a bit higher than normal then idle stared to rise on it's own all the way to 1000-1100ish and got kinda choppy/rough. I turned truck off, deleted the codes and started truck back up to idle for a bit. Checked codes again and this time only through code for P0278(cylinder #6). Deleted that code again and started back up...idled fine this time. Took for a drive...all seemed good, checked for codes and there were none this time. Gonna keep an eye on it and see if they keep popping back up. If they do, i'm gonna yank all of them and send them out to have them checked out. Now, if it's a contribution/balance code...does that pretty much narrow it down to a rubber o-ring or copper washer? What else can through contribution/balance codes....can a faulty spool valve or wiring(injector harness or injector plug) cause a contribution/balance code?