I don't know if you're using one or not Marv but after the races yesturday a few of us were doing some bench racing when one of the guys said he had a high speed miss on the top end for quite awhile.Of course I was all ears and what he said was,somewhere on the internet he found some info regarding K&N filter tops with cowl inductions.For some reason the filter top creates a vacum and causes a lean condition which in turn can cause a missfire.He said when he got rid of the top his miss went with it.
I put a cowl hood on this year and use the K&N top so maybe that has something to do with mine as well.

I've ran with and without a filter (don't use the K&N top) and found nothing in ET. With the surprise dust storms we get down here I just run with it in place all the time. Ran with and without the filter and or airpan sealed to the cowl hood and the cooler air did help ET but did not a stinking thing for my rpm problem.

Well it was worth a try and may help me.