That "kaBOOM" is probably the cause of the constant problems.  When a Holley has a backfire it ruins the powervalve.  Doesn't run right until it is fixed.  I think there is some sort of an update kit which protects the powervalve when it experiences a backfire but don't hold me to that.

I agree 100% with the Edelbrock.  Darn good carb if you have to have a carb.