any one running a blower?

To me it just sounds like you have a rich condition at idle,5 psi should be good , I dont know what you have done with your carbs. I would start with the basics of checking float levels, running all the idle mixture screws all the way in and set them the same , you will have to play with them but you may have to set them all as low as 1/2 turn out.
Make sure that if you turn the screws in while running it effects the idle, should start to die as you crank them in. Leaking power valve from a backfire if you have them would cause rich condition .
One or both of the carbs idle set too high uncovering and pulling fuel from another circuit in the carb.
Double check timing roots love lots of timing check out bds tech info:

http://www.blowerdriveservice.com/faq.php