After reading all of these threads and posts about the head/valve issue, and years of being a shade tree mechanic, I have noticed a slight rattle that can best be decribed as valve rattle. It is very faint, infact I can hear it because I know what to listen for, but my girlfriend says it sounds normal to her. My vehicle falls within the VIN range, and I have about 15,300 miles on it, so all of this points in the right direction. My question is for those that have had the issue if they experienced any excessive rattle before, or along with the rough idle and bad fuel economy. So far I don't have either of those symptoms, nor has my check engine light come on. I do experience occasional minor preignition from a standing start, which has me baffled because I only run Top Tier gas, i.e. Shell. I don't think these two are related though.