I agree with Maxwedge on the miss after engagement, however if it is during engagement, you may have the valve body wear as described in the link below. The second link is for the intecepter, which will delay lockup until a higher speed is reached. This will make the misfire problem (if you have that) less noticeable.
http://www.my3cents.com/showReview.cgi?id=8968
http://keyword.netscape.com/ns/boomf...ntecepter.html
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