I put the Bozio's in about a month ago. Big improvement on start up smoke and idle(at first). Man are these things noisy! I've driven it over a thousand miles and the nailing hasn't gone down any. The rough idle has come back especially when cold. I think my old wagon is just getting tired. Any ideas why the nailing has persisted?

Thanks

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Brad
1981 300TD - daily driver
1963 Chevy II
2001 F-250 7.3 Power Stroke