You said your running a 6.5" power valve, but only pulling 7-8"hg at idle. Power valve should be half of vacuum so 3.5" to 4". It's definitely opening too soon based on those numbers.
Not true and even w/a p/v open at idle that circuit is not(shouldn`t) be active. You gauge p/v size on your average cruising NOT idle so if you cruise at say 10" of vacuum, then a p/v below that such as an 8.5-9.5 would be a good starting point but not the end all................
