i have a 2006 chevy silverado 4x4 crew cab 5.3L and the check engine light appeared last week, i don´t remember the exact code oon the scanner but it has something to do with the emission system and the egr valve. before i got it scanned i thought it would be the oil, but i changed it and it kept doing the some noise, then i changed the spark plugs and still had the same noise, i took it to autozone in order to get it scanned and the result was that emission problem, i cleaned the egr valve and the throttle as well with a special spray and the noise is still there. Does anyone have the same problem? sorry about my bad english but i live in mexico i hope you can understand what i´m trying to explain