I have a bad cold idle, and am down about 500rpm, and 10mph at WOT. I do not have a check valve on my Holley 750carb, and have had this issue before, but always had a friend that recently passed on take care of my carb...so I just dropped it off, and got it back- never knowing what was done to it.
Do these symptoms seem like something a blown power valve would cause?
No other changes have been made to the boat.