If it goes away with higher octane fuel then it is an engine ping. If it doesn't, you may need to look elsewhere. I suspect it is just pinging. Sometimes winter fuel on a warm day will do this even if everything else is OK. If it is a ping, then do clean the injectors and the throttle body for certain. Cleaning the rest of the intake cannot hurt. Cleaning the EGR passages may help as well.
For what it is worth, I also usually use Chevron 87 in my car with no problem. My car does call for 91 Octane since it is an SVT, but as long as everything is clean, the 87 Octane works fine. I have only heard my car ping twice, both times it was on a hot winter day. We do have a few of those in southern California.
