LightMan, the noise you are experiencing sounds very much like the one I had. Good Luck!

After I took the manifold down I found about 0.1 inches of black build up in the runners and the ERG. I scraped as much as I could without markinmg the aluminum housing. Should I use a special degreaser to completely remove the build-up? I guess the air flow passeges have been reduced quite significantly.

Pat

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pat201