I have a 2003 S-10 Blazer that has developed an off idle ping/rattle, truck only has 13,000 miles. Possible EGR problem, I filled it with 91 octane and marvel mystery oil seemed to help a little. On a cold engine can pull away without noise, noticable when warmed up. Any suggestions? It's not terribly bad, and only when starting out in first gear, no noise when going up a hill at speed. Is this acceptable?

Look at this thread
http://www.automotiveforums.com/vbulletin/showthread.php?t=283211
If you care to try it, it might just fix your problem.

I might be wrong, but from the sounds of it to me you've got an engine full of carbon.

Do the 2003 have an egr?I thought i read somewhere they didnt or it was moved somewhere else.I know someone out their knows for sure.

In th 2003 the EGR has been internalized...

In th 2003 the EGR has been internalized...
Thanks for the reply's I figured it was carbon build up and could'nt find the EGR valve with a quick check, so maybe it has been eliminated or internal for 2003. Will take it on a trip use 91-93 octane and Marvel and see what happens. Thanks, Hall

Don't use marvel for that, use Seafoam