I didn't put it together until reading this post but I've had the same problem with a new shake at idle. I used gray bottle of P.S. and layed it on thick. Filters didn't look too bad when I changed them out last weekend. I even filled up the screw on filter with straight P.S. Idle is better now with new filters but wonder if it loosens up a lot of gunk in the tank?

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1984 300d
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