Failed Emissions a 4th time!

[Daveyboy1983]

Ok '86 GMC 305 with a 600cfm Holley carb and I have failed emissions again for the same things High CO and High HC I have Changed the oil, Changed the PCV valve, put in plugs that are 2 heat ranges hotter, rejeted the carb for my altitude, set the floats, and adjusted the air fuel mix and the truck is running great!... I have all of my stock emissions controls hooked up accept the EGR Valve the PO took it off when he put the holley on because of a clearance issue I am stuck and can not figure out why this thing wont pass... Do I have a bad power valve? Bad Cat? Im not really good at diagnosing emission issues and dont want to start throwing parts at it and it not solve my problems any help would be great thanks...